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BEGIN:VEVENT
SUMMARY:Advanced Virgo detector: the path from O2 to O3
DTSTART;VALUE=DATE-TIME:20190220T152700Z
DTEND;VALUE=DATE-TIME:20190220T154400Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83780@agenda.infn.it
DESCRIPTION:Speakers: Annalisa Allocca ()\nGravitational Waves discovery h
as recently be announced by the LIGO and the Virgo collaborations.\nDue to
their weak amplitude\, Gravitational Waves are expected to produce a very
small effect on free- falling masses\, which undergo a displacement of th
e order of 10^(-18) m for a km-scale mutual distance. This discovery showe
d that interferometric detectors are suitable to reveal such a feeble effe
ct\, and therefore represent a new tool for astronomy\, astrophysics and c
osmology in the understanding of the Universe.\nTo better reconstruct the
position of the Gravitational Wave source and increase the signal-to-noise
ratio of the events by means of multiple coincidence\, a network of detec
tors is \nnecessary. In the USA\, a couple of twin 4 kilometer-long arms d
etectors\, which are placed in Washington State and Louisiana\, constitute
the LIGO project. Advanced Virgo (AdV) is a 3 kilometer-long arms second
generation interferometer situated in Cascina\, near Pisa in Italy.\nOn Au
gust 1st 2017\, Virgo has joined LIGO in the second observation run (O2) f
or about one month\, during which Virgo has detected for the first time a
Gravitational Wave produced by binary black holes and binary neutron stars
systems. In view of the next science run which will start in Spring \n201
9\, hardware upgrades have been performed\, such as monolithic suspension
installation and injection of squeezed light\, which have improved the det
ector performances in the mid-low and high frequency range\, respectively.
Furthermore\, thanks to unceasing noise hunting and commissioning \nactiv
ities addressed towards the noise reduction and fine tuning of the interfe
rometer working point\, a broad improvement of the detector sensitivity ov
er the whole frequency range was achieved. \nThanks to all of these action
s\, Advanced Virgo will be able to join the third observation run with a s
ensitivity two times\nhigher than it was during O2.\n\nhttps://agenda.infn
.it/event/15395/contributions/83780/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83780/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Multimessenger constraints of neutron star equation of state
DTSTART;VALUE=DATE-TIME:20190220T164800Z
DTEND;VALUE=DATE-TIME:20190220T164900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83806@agenda.infn.it
DESCRIPTION:Speakers: Margherita Fasano (La Sapienza - University of Rome)
\nConstraining the equation of state (EoS) of cold dense matter in neutron
stars (NS) is a major science goal for observing programmes conducted wit
h X-ray\, \nradio\, and gravitational wave telescopes. In this talk we de
monstrate how to combine gravitational-wave and electromagnetic observatio
ns in order to solve \nthe relativistic inverse stellar problem\, i.e. to
reconstruct the main features of the EoS. Using a full Bayesian analysis\,
we apply this approach to the \ndata obtained by the LIGO/Virgo collabora
tion for the binary neutron star detection GW170817\, setting new constrai
nts on the parameters that characterise \nthe behaviour of matter at supra
-nuclear densities.\n\nhttps://agenda.infn.it/event/15395/contributions/83
806/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83806/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the viability of regular black holes
DTSTART;VALUE=DATE-TIME:20190220T174000Z
DTEND;VALUE=DATE-TIME:20190220T174100Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83804@agenda.infn.it
DESCRIPTION:Speakers: Francesco Di Filippo (SISSA)\nRegular models of blac
k holes replace the central singularity with a \nnonsingular spacetime reg
ion\, in which an effective classical geometric \ndescription is available
. It has been argued that these models provide \nan effective\, but comple
te\, description of the evaporation of black \nholes at all times up to th
eir eventual disappearance. However\, I will \nshow that known models fail
to be self-consistent: the regular core is \nexponentially unstable again
st perturbations with a finite timescale\, \nwhile the evaporation time is
infinite\, therefore making the instability \nimpossible to prevent.\n\nh
ttps://agenda.infn.it/event/15395/contributions/83804/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83804/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Traversable Casimir Wormholes
DTSTART;VALUE=DATE-TIME:20190220T173900Z
DTEND;VALUE=DATE-TIME:20190220T174000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83809@agenda.infn.it
DESCRIPTION:Speakers: Remo Garattini (Università di Bergamo)\nAfter a bri
ef description of what is a traversable wormhole we describe the connectio
n between traversability and the Casimir effect. With the help of an equat
ion of state we also discuss different form of solutions generated by the
Casimir source. A connection with the Quantum Weak Energy Condition is als
o presented.\n\nhttps://agenda.infn.it/event/15395/contributions/83809/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83809/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Mixmaster Universe in the f (R) gravity.
DTSTART;VALUE=DATE-TIME:20190220T173800Z
DTEND;VALUE=DATE-TIME:20190220T173900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83872@agenda.infn.it
DESCRIPTION:Speakers: Massimo luca emiliano Carinci (ICRA)\nWe consider th
e dynamics of the Mixmaster Universe\, focusing on the Bianchi IX cosmolog
ical model (this model have a closed Universe with a spherical topology).
We use f (R) gravity\, which is the simplest modification of the general r
elativity\, considering the Palatini formalism\, and compare the results w
ith those of the quadratic correction. To describe the Mixmaster model\, w
e use the Misner Chitrè – like variables\, in the scalar-tensor framewo
rk. The form of the potential well depends on the self interacting scalar
field potential. We start our work introducing f (R) gravity theories and
their most important aspects covering the largest portion of the literatur
e. Furthermore\, we demonstrate the non-chaotic nature of the Mixmaster mo
del\, if it is described by the scalar-tensor version of the f (R) gravity
. This work\, derived in the homogeneous cosmological setting\, can be eas
ily extended to the inhomogeneous case.\n\nhttps://agenda.infn.it/event/15
395/contributions/83872/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83872/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shedding light on the Milky Way with Gaia DR2
DTSTART;VALUE=DATE-TIME:20190220T173700Z
DTEND;VALUE=DATE-TIME:20190220T173800Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83871@agenda.infn.it
DESCRIPTION:Speakers: Mariateresa Crosta (INAF-OATo)\, Mario Lattanzi (INA
F-OATo)\nNowadays\, our modeling of the Universe depends critically on our
understanding of gravity\; despite the fact General Relativity (GR) is th
e standard theory of gravity\, deviations from GR could profoundly impact
our conclusions on the best theory suitable to explain the "dark" ingredie
nts that make up the Universe. On the other hand\, experimental verificati
ons of the GR weak effects are difficult\, but could be as fundamental and
complementary as any other observations that test manifestly the validity
of Einstein's field equations\, which underpin strong gravity. \nGaia-lik
e missions are offering the unique possibility of being a multi laboratory
for extensively testing weak gravitational fields at local (Solar System
) and more distant (MIlky Way) scales. \nIn particular\, the potential of
Gaia is to probe the validity of GR by testing the structure of our Galaxy
as a product of the cosmological evolution shaped by gravity (Local Cosmo
logy)\, namely the relations among baryonic structures (and their evolutio
n) and the dark components of the Universe. \nIn particular\, we present t
he first attempt to apply the relativistic kinematics delivered by Gaia to
trace the MW rotation curves within a general relativistic scenario.\n\nh
ttps://agenda.infn.it/event/15395/contributions/83871/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83871/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Partition function in conformal gravity
DTSTART;VALUE=DATE-TIME:20190220T173600Z
DTEND;VALUE=DATE-TIME:20190220T173700Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83870@agenda.infn.it
DESCRIPTION:Speakers: Rachwal Leslaw (Czech Technical University)\nWe deri
ve the form of the partition function in conformal gravity using an extend
ed form of the Faddeev-Popov method. The method uses conformal gauge fixin
g and special (third) conformal ghosts. In this way\, at one-loop\, the th
eory is proven to be conformally invariant also on the quantum level witho
ut performing an additional final conformal transformation. The partition
function is discussed on a general background as well as on Ricci-flat and
maximally symmetric.\n\nhttps://agenda.infn.it/event/15395/contributions/
83870/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83870/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cosmology with gravitational waves from compact binary coalescence
s
DTSTART;VALUE=DATE-TIME:20190220T173500Z
DTEND;VALUE=DATE-TIME:20190220T173600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83849@agenda.infn.it
DESCRIPTION:Speakers: Archisman Ghosh (Nikhef)\nGW170817 with its coincide
nt optical counterpart has led to a first "standard siren" measurement of
the Hubble constant independent of the cosmological distance ladder. The S
chutz "statistical" method\, which is expected to work in the absence of u
niquely identified hosts\, has also started bringing in its first estimate
s. In this talk we report the current results of the gravitational-wave me
asurement of the Hubble constant and discuss the prospects with observatio
ns during the upcoming runs of the Advanced LIGO-Virgo detector network.\n
\nhttps://agenda.infn.it/event/15395/contributions/83849/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83849/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Astrophysical gravitational waves in conformal gravity models
DTSTART;VALUE=DATE-TIME:20190220T173400Z
DTEND;VALUE=DATE-TIME:20190220T173500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83844@agenda.infn.it
DESCRIPTION:Speakers: Patric Hölscher ()\nWe investigate the gravitationa
l radiation from binary systems in conformal gravity (CG) and conformal Ei
nstein-Weyl gravity (CEWG). CG might explain observed galaxy rotation curv
es without dark matter\, and both models are of interest in the context of
quantum gravity. Gravitational radiation emitted by compact binaries allo
ws us to strongly constrain both models. \nWe derive the linearized fourth
-order equation of motion for the metric\, which describes massless and ma
ssive modes of propagation and we show that the gravitational radiation is
due to the time-dependent quadrupole moment of a nonrelativistic source.
Further\, we derive the gravitational energy-momentum tensor for both mode
ls and apply our findings to the case of close binaries on circular orbits
.\nOur results are that in CG one cannot explain the orbital decay of bina
ry systems via gravitational radiation\, and replace dark matter simultane
ously. In CEWG with small masses of the graviton\, again one cannot reprod
uce the orbit of binaries by the emission of gravitational waves. On the o
ther hand\, for large graviton masses\, the orbital period of compact bina
ries is in agreement with the data\, as CEWG reduces to GR in this limit.\
n\nhttps://agenda.infn.it/event/15395/contributions/83844/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83844/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Inertial mode excitation of long-lived remnants of binary neutron
star mergers
DTSTART;VALUE=DATE-TIME:20190220T173300Z
DTEND;VALUE=DATE-TIME:20190220T173400Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83866@agenda.infn.it
DESCRIPTION:Speakers: Michele Pasquali (Istituto Nazionale di Fisica Nucle
are)\nWe show that in the post-merger phase of binary neutron star (BNS) m
erger are present convective instabilities that excite inertial mode oscil
lations. These oscillations emit gravitational waves in the frequency band
where ground-based detectors are within reach of planned third-generation
detectors and could be used also as sensitive probes of the rotational an
d thermal state of matter in the neutron star remnant. Within the limits o
f the input physics of our simulations (which neglect magnetic fields and
neutrino transport) their presence appear to be quite general for remnants
that live more than 50 ms and show up for four different equations of sta
te (EOS)\, parametrized as piecewise polytropics plus a thermal component
with $\\Gamma = 1.8$. We also analyze the gravitational wave signal emitte
d by the remnant after the merger for each EOS in order to characterize th
e rate of change of the frequencies and the damping of the amplitudes for
both the main and excited mode.\n\nhttps://agenda.infn.it/event/15395/cont
ributions/83866/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83866/
END:VEVENT
BEGIN:VEVENT
SUMMARY:An electrostatic potential in curved spaces
DTSTART;VALUE=DATE-TIME:20190220T173200Z
DTEND;VALUE=DATE-TIME:20190220T173300Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83865@agenda.infn.it
DESCRIPTION:Speakers: Gopinath Kamath (Indian Institute of Technology Tiru
pati)\nFollowing Whittaker(*Proc.Roy.Soc.A***116**\,720(1927)) we derive t
he partial differential equation whose solution is the electrostatic poten
tial in curved spaces with the metric given :\n\na.in 2 + 1 dimensions by
i)S.Deser\,R.Jackiw and G.'tHooft\,*Ann.Phys.***152**\,220(1984) and G.Cl
ement\,*Int.J.Theor.Phys.***24**\,267(1985)and by ii)M.Banados\,C.Teitelbo
im and J.Zanelli\,*Phys.Rev.Lett.***69**\,1849(1992) and \n\nb.in 3 + 1 d
imensions by C.S.Trendafilova and S.Fulling\,*Eur.J.Phys.***32**\,1663(201
1)\n\nWith an exact solution to the partial differential equation as the o
bjective\,the telling interest here is the contrast between the resulting
partial differential equations in 3 + 1 dimensions from the use of the Sch
warzschild metric -and this was dealt with in detail by Whittaker(see eq.(
25) et seq. in the reference cited) -versus the cylindrically symmetric me
tric given by Trendafilova and Fulling in item b. above\n\nFinally\, in th
e planar case an exact form for the electrostatic potential seems less acc
essible for the Banados-Teitelboim-Zanelli metric relative to the Deser-Ja
ckiw-'tHooft and Clement solution.\n\nhttps://agenda.infn.it/event/15395/c
ontributions/83865/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83865/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Spectrum of cosmological correlation from vacuum fluctuation of St
ringy Axion in entangled De Sitter space
DTSTART;VALUE=DATE-TIME:20190220T173100Z
DTEND;VALUE=DATE-TIME:20190220T173200Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83846@agenda.infn.it
DESCRIPTION:Speakers: Sayantan Choudhury (Max Planck Institute for Gravita
tional Physics\, potsdam.)\nIn this work\, we study the impact of quantum
entanglement on the two-point correlation function and the associated prim
ordial power spectrum of mean square vacuum fluctuation in a bipartite qua
ntum field theoretic system. The field theory that we consider is the effe
ctive theory of axion field arising from Type IIB string theory compactifi
ed to four dimensions. We compute the expression for the power spectrum of
vacuum fluctuation in three different approaches\, namely (1) field opera
tor expansion (FOE) technique with the quantum entangled state\, (2) reduc
ed density matrix (RDM) formalism with mixed quantum state and (3) the met
hod of non-entangled state (NES). For massless axion field\, in all these
three formalism\, we reproduce\, at the leading order\, the exact scale-in
variant power spectrum which is well known in the literature. We observe t
hat due to quantum entanglement\, the sub-leading terms for these thee for
malisms are different. Thus\, such correction terms break the degeneracy a
mong the analysis of the FOE\, RDM and NES formalisms in the super-horizon
limit. On the other hand\, for massive axion field\, we get a slight devi
ation from scale invariance and exactly quantify the spectral tilt of the
power spectrum in small scales. Apart from that\, for massless and massive
axion field\, we find distinguishable features of the power spectrum for
the FOE\, RDM\, and NES on the large scales\, which is the result of quant
um entanglement. We also find that such large-scale effects are comparable
to or greater than the curvature radius of the de Sitter space. Most impo
rtantly\, in the near future\, if experiments probe for early universe phe
nomena\, one can detect such small quantum effects. In such a scenario\, i
t is possible to test the implications of quantum entanglement in primordi
al cosmology.\n\nhttps://agenda.infn.it/event/15395/contributions/83846/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83846/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Casimir effect as a probe for extended theories of gravity
DTSTART;VALUE=DATE-TIME:20190220T173000Z
DTEND;VALUE=DATE-TIME:20190220T173100Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83839@agenda.infn.it
DESCRIPTION:Speakers: Luciano Petruzziello (Istituto Nazionale di Fisica N
ucleare)\nIn this talk\, I explore the Casimir effect for a massless scala
r field in the context of a generic curved background. In this perspective
\, the mean vacuum energy density and the pressure between the binding pla
tes are the relevant physical objects to evaluate. After the above general
discussion\, a systematic procedure to derive interesting pieces of infor
mation on the free parameters of extended theories of gravity is presented
. In particular\, I focus the attention on some recent results regarding t
he Standard Model Extension and several quadratic models of gravity.\n\nht
tps://agenda.infn.it/event/15395/contributions/83839/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83839/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Study of Semiclassical Instability of the Schwarzschild AdS Black
Hole in the Large D Limit
DTSTART;VALUE=DATE-TIME:20190220T172900Z
DTEND;VALUE=DATE-TIME:20190220T173000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83837@agenda.infn.it
DESCRIPTION:Speakers: Amruta Sadhu (IISER Pune)\nWe analyze the semiclassi
cal stability of the Schwarzschild AdS black hole\nin the Euclidean partit
ion function approach. We perform this computation\nin the large D limit a
nd focus on scalar perturbations. We obtain the equa-\ntions for non-spher
ically symmetric scalar perturbations in a simple form.\nFor a class of pe
rturbations stability is demonstrated by the S-deformation\nmethod. For so
me other classes we rule out unstable modes of O(D^2). We\nalso analyze th
e spherically symmetric perturbations and demonstrate the\nappearance of a
n unstable mode for small black holes in the large D limit.\nWe obtain an
expression for the eigenvalue corresponding to the unstable\nmode to next
to leading order in a 1/D expansion. This result agrees with\na previously
obtained numerical bound on this eigenvalue. For cosmological\nconstant z
ero\, our answer matches a previous result obtained for the corre-\nspondi
ng eigenvalue for the D dimensional Schwarzschild-Tangherlini black\nhole
to next to leading order in a 1/D expansion.\n\nhttps://agenda.infn.it/eve
nt/15395/contributions/83837/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83837/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cooperative Dynamical Processes: the Emergence of Relativistic Qua
ntum Theory
DTSTART;VALUE=DATE-TIME:20190220T172800Z
DTEND;VALUE=DATE-TIME:20190220T172900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83843@agenda.infn.it
DESCRIPTION:Speakers: Petr Jizba (Czech Technical University in Prague)\nS
cenarios that strive to describe quantum theory as an emergent\, non-primi
tive concept typically run into difficulties when trying to address a rela
tivistic generalization. In this talk we discuss a possible way out of thi
s situation by showing that the observed relativistic behavior in the quan
tum world might well be just a statistically emergent phenomenon out of de
eper no-relativistic level of quantum dynamics. We start by discussing com
plex dynamical systems whose statistical behavior can be explained in term
s of a superposition of simpler underlying dynamics — the so-called supe
rstatistics paradigm. Then we go on by showing that the combination of two
cornerstones of contemporary physics — namely Einstein’s special rela
tivity and quantum-mechanical dynamics is mathematically identical to a co
mplex dynamical system described by two interlocked processes operating at
different energy scales. The combined dynamic obeys Einstein’s special
relativity even though neither of the two underlying dynamics does. This i
mplies that Einstein’s special relativity might well be an emergent conc
ept in the quantum realm.\n\nTo model the double process in question\, we
consider quantum mechanical dynamics in a background space consisting of a
number of small crystal-like domains varying in size and composition\, kn
own as polycrystalline space. There\, particles exhibit a Brownian motion.
The observed relativistic dynamics then comes solely from a particular gr
ain distribution in the polycrystalline space. In the cosmological context
such distribution might form during the early universe’s formation.\nEn
suing implications for quantum field theory and cosmology (leptogenesis) w
ill be also briefly discussed.\n\nRelated articles:\n[1] P. Jizba and F. S
cardigli\, Special Relativity Induced by Granular Space\, Eur. Phys. J. C
(2013) 73: 2491\n[2] P. Jizba and F. Scardigli\, The emergence of Special
and Doubly Special Relativity\, Phys. Rev. D (2012) 86: 025029\n[3] P.Jizb
a and H. Kleinert\, Superstatistics approach to path integral for a relati
vistic particle\, Phys. Rev. D (2010) 82: 085016\n\nhttps://agenda.infn.it
/event/15395/contributions/83843/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83843/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Scattering of gravitational plane waves by a compact body
DTSTART;VALUE=DATE-TIME:20190220T172700Z
DTEND;VALUE=DATE-TIME:20190220T172800Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83833@agenda.infn.it
DESCRIPTION:Speakers: Thomas Stratton (University of Sheffield)\nWe consid
er time-independent scattering of gravitational waves by a compact horizon
-less body such as a neutron star. The neutron star is modelled with a pol
ytropic equation of state. The metric perturbation in the exterior can be
solved for using the gauge invariant master functions and formalism presen
ted by Martel and Poisson [2005]. For the interior we work in Regge-Wheele
r gauge and solve the perturbed Einstein field equations for odd and even
parity. We will show that in this scenario\, there can be rainbow scatter
ing\, similar to that seen in nuclear experiments. An associated caustic
(a focusing of null geodesics) forms near the body’s surface. This featu
re is imitated in the wave picture. We will compare our results with blac
k hole scattering studies.\n\nhttps://agenda.infn.it/event/15395/contribut
ions/83833/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83833/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nonlocal generalization of Galilean theories and gravity
DTSTART;VALUE=DATE-TIME:20190220T172600Z
DTEND;VALUE=DATE-TIME:20190220T172700Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83829@agenda.infn.it
DESCRIPTION:Speakers: Luca Luca Buoninfante ()\nIn this talk we will consi
der the possibility to enlarge the class of symmetries under which a local
(polynomial) action is invariant by introducing nonlocal (non-polynomial)
operators. In particular\, we will show how to construct nonlocal actions
\, consisting of infinite order derivatives\, which are invariant under a
wider class of symmetries\, containing the Galilean shift symmetry as a su
bclass. Motivated by this\, we will consider the case of a scalar field an
d discuss the pole structure of the propagator which has infinitely many c
omplex conjugate poles\, but satisfies the tree-level unitarity. We will a
lso consider the possibility to construct UV complete Galilean theories by
showing how the ultraviolet behavior of loop integrals can be ameliorated
. Moreover\, we will consider kinetic operators respecting the same symmet
ries in the context of linearized gravity. In such a scenario\, the gravit
on propagator turns out to be ghost-free and the spacetime metric generate
d by a point-like source is nonsingular. These new models might open a new
branch of nonlocal theories.\n\nhttps://agenda.infn.it/event/15395/contri
butions/83829/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83829/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Curvature for nonperturbative quantum gravity
DTSTART;VALUE=DATE-TIME:20190220T164700Z
DTEND;VALUE=DATE-TIME:20190220T164800Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83828@agenda.infn.it
DESCRIPTION:Speakers: Nilas Falster Klitgaard (Radboud University)\nOne fr
uitful approach to quantum gravity has been the framework of Causal Dynami
cal Triangulations (CDT). This path integral approach describes space-time
in a nonperturbative and background-independent manner. The Planckian reg
ime is characterized by wild and highly non-classical geometries and gener
al relativity is recovered as an effective theory in the IR limit.\n\nAn i
mportant question is how to describe operators that are meaningful at the
Planck length and flow towards classical equivalents in the IR limit. In t
his talk I will discuss the construction of "Quantum Ricci Curvature". Thi
s novel definition of a quantum implementation of the classical Ricci tens
or relies on the average distance between spheres. It contains a natural s
cale in terms of the radius of these spheres and is applicable in a large
variety of situations. I will show how quantum Ricci curvature is construc
ted and measured and if time permits I will discuss the results obtained
for dynamical triangulations. This is based on arXiv 1712.08847 and 1802.1
0524\n\nhttps://agenda.infn.it/event/15395/contributions/83828/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83828/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravitational "Magnus" Effect
DTSTART;VALUE=DATE-TIME:20190220T172500Z
DTEND;VALUE=DATE-TIME:20190220T172600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83826@agenda.infn.it
DESCRIPTION:Speakers: Filipe Costa (CAMGSD - Instituto Superior Técnico\,
Lisbon)\nIt is well known that a spinning body moving in a fluid suffers
a force orthogonal to its velocity and rotation axis --- it is called the
Magnus effect. Recent simulations of spinning black holes and (indirect) t
heoretical arguments suggest that a somewhat analogous effect may occur fo
r purely gravitational phenomena. The magnitude and precise direction of
this "gravitational Magnus effect" is however still the subject of debate.
Starting from the rigorous equations of motion for spinning bodies in Gen
eral Relativity (Mathisson-Papapetrou equations)\, we show that indeed suc
h an effect takes place. We compute it explicitly for some astrophysical s
ystems of interest: galactic dark matter haloes\, black hole accretion dis
ks\, and the cosmological FLRW background. It is seen to lead to secular o
rbital precessions potentially observable by future astrometric experiment
s and gravitational-wave detectors.\n\nhttps://agenda.infn.it/event/15395/
contributions/83826/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83826/
END:VEVENT
BEGIN:VEVENT
SUMMARY:ELXIS: a satellite to accurately measure general relativistic drag
ging effects
DTSTART;VALUE=DATE-TIME:20190220T172400Z
DTEND;VALUE=DATE-TIME:20190220T172500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83825@agenda.infn.it
DESCRIPTION:Speakers: Lorenzo Iorio (MIUR-Istruzione)\nUsing a geocentric
ecliptical coordinate system to analyze the data of a proposed new Earth's
satellite\, provisionally named ELXIS\, in a circular orbit perpendicular
to both the equator and the reference direction of the Vernal Equinox sho
uld allow\, in principle\, to measure the general relativistic Lense-Thir
ring and De Sitter effects on the satellite's inclination $I$ and node $\\
Omega$ to a relative accuracy of $\\simeq 10^{-2}\,~10^{-5}$\, respectivel
y. Indeed\, the long-term perturbations on $I\,~\\Omega$\, referred to the
ecliptic\, due to the zonal harmonic coefficients $J_\\ell\,~\\ell=2\,3\,
4\,5\,\\ldots$ of the geopotential vanish for $e=0\,~I = \\Omega = 90\\deg
$. Departures $\\Delta I=\\Delta\\Omega\\simeq 0.01-0.1\\deg$ from such an
ideal orbital configuration would not compromise the stated accuracy goal
s. The most insidious competing perturbations are due to the ocean compone
nt of the $K_1$ tide of degree $\\ell=2$ and order $m=1$: they do not vani
sh for $I = \\Omega = 90\\deg$\, and our knowledge of its tidal height $C_
{2\,1\,K_1}^{+}$ is relatively inaccurate. A suitable linear combination o
f the rates of change of $I\,~\\Omega$ allows to cancel out them and enfor
ce the De Sitter effect. By assuming a relative uncertainty of the order
of $\\simeq 10^{-3}$ in $C_{2\,1\,K_1}^{+}$ from a comparison of some rath
er recent global ocean tide models\, the resulting systematic bias on each
of the Lense-Thirring precessions would be at the percent level. Other so
urces of potential systematic uncertainties like the 3rd-body perturbation
s due to the Moon and the non-gravitational accelerations allow to meet th
e desired accuracy levels.\n\nhttps://agenda.infn.it/event/15395/contribut
ions/83825/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83825/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Correspondence Between Ricci-Based Theories of Gravity and General
Relativity
DTSTART;VALUE=DATE-TIME:20190220T172300Z
DTEND;VALUE=DATE-TIME:20190220T172400Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83823@agenda.infn.it
DESCRIPTION:Speakers: Emanuele Orazi ()\nDriven by the the fact that a wid
e family of Ricci-based metric-affine theories of gravity can be reduced t
o a metric compatible framework\, a formal correspondence between the spac
e of solutions of these generalized gravity theories and the space of solu
tions of general relativity will be presented. The correspondence will be
detailed in the cases where modified gravity is coupled to scalar and char
ged matter. These results allows to use well-established methods and resul
ts from General relativity to explore new gravitational physics beyond it.
\n\nThe presentation will be based on the following recent publications :
arXiv:1810.04239\, arXiv:1807.06385\, arXiv:1705.03806.\n\nhttps://agenda
.infn.it/event/15395/contributions/83823/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83823/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Renormalised vacuum polarisation on topological black holes
DTSTART;VALUE=DATE-TIME:20190220T172200Z
DTEND;VALUE=DATE-TIME:20190220T172300Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83819@agenda.infn.it
DESCRIPTION:Speakers: Thomas Morley (University of Sheffield)\nAnti-de Sit
ter spacetime is a solution of Einstein’s equations with a negative cosm
ological constant. This fact allows for unusual black hole solutions with
non-spherical horizon topology. We calculate the renormalised vacuum polar
isation for black holes with spherical\, flat and hyperbolic event horizon
s\, following the “extended coordinates” method\, which uses a mode-su
m representation for the Hadamard parametrix. Renormalisation counter term
s are subtracted from the Green’s function mode-by-mode\, leaving each i
ndividual term manifestly finite.\n\nhttps://agenda.infn.it/event/15395/co
ntributions/83819/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83819/
END:VEVENT
BEGIN:VEVENT
SUMMARY:How to compute the Cosmological Constant in Distorted Gravity
DTSTART;VALUE=DATE-TIME:20190220T172100Z
DTEND;VALUE=DATE-TIME:20190220T172200Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83812@agenda.infn.it
DESCRIPTION:Speakers: Remo Garattini (Università degli Studi di Bergamo)\
nWe compute the Zero Point Energy (ZPE) induced by quantum fluctuations ar
ound a fixed background with the help of a reformulation of the Wheeler-De
Witt equation. A variational approach is used for the calculation with Gau
ssian Trial Wave Functionals. The one loop contribution of the graviton to
the ZPE is extracted keeping under control the UltraViolet divergences by
means of a distorted gravitational field knows as Gravity's Rainbow. The
finite ZPE is here interpreted as an induced Cosmological Constant. A comp
arison with other methods of keeping under control ultraviolet divergences
is also discussed.\n\nhttps://agenda.infn.it/event/15395/contributions/83
812/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83812/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gamma-ray bursts and gravitational waves joint analysis with the L
IGO-Virgo network
DTSTART;VALUE=DATE-TIME:20190220T172000Z
DTEND;VALUE=DATE-TIME:20190220T172100Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83815@agenda.infn.it
DESCRIPTION:Speakers: Francesco Carotenuto (Università degli Studi di Rom
a 'La Sapienza')\nIn the context of the unmodelled search for gravitationa
l waves associated to *gamma-ray bursts* (GRB)\, we present a sensitivity
study conducted using *X-Pipeline*\, a software which combines the data fr
om LIGO and Virgo in correlation with the GRB direction in the sky. The go
al is to understand how the addition of Virgo to the network of interferom
eters impacts the sensitivity of the search. The overall sensitivity\, lim
ited by non-stationary noise\, is estimated through the efficiency in reco
vering simulated gravitational waves signals injected in the data\, and th
en it is compared to the sensitivity obtained without including Virgo. For
4 out of 9 GRBs detected in August 2017\, adding Virgo results in lower u
pper limits on the amplitudes of the injected waveforms in the [20\, 500]
Hz band\, improving the sensitivity up to a factor of ~60%. For the 5 GRBs
left\, the addition of Virgo reduced the sensitivity up to ~25%. We find
that the crucial factor is the ratio between the detector angular response
and its noise power spectrum: when this quantity computed for Virgo is sm
aller than for LIGO\, the Virgo inclusion results in a better sensitivity.
This gives us a metric for the Virgo inclusion in this search for the nex
t observing run.\n\nhttps://agenda.infn.it/event/15395/contributions/83815
/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83815/
END:VEVENT
BEGIN:VEVENT
SUMMARY:New method to observe gravitational waves emitted by core collapse
supernovae
DTSTART;VALUE=DATE-TIME:20190220T171900Z
DTEND;VALUE=DATE-TIME:20190220T172000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83821@agenda.infn.it
DESCRIPTION:Speakers: Irene Di Palma (ROMA1)\nGravitational waves (GWs) ha
ve been detected from mergers of binary black holes and binary neutron sta
rs.\nCore collapse supernovae (CCSNe) are recognized as the most energetic
explosions in the modern Universe\nThe main reason GWs from CCSN have not
yet been detected is the low event rate\, about one per century\,\nobserv
able within the Milky Way.\nWe report on the construction of a Convolution
al Neural Network to focus on gravitational waves produced in one of the m
ost dramatic events in the cosmos\, supernova explosions.\nWe use only whi
tened time series of measured gravitational-wave strain as an input\, and
we train and test on simulated core-collapse supernovae signals in synthe
tic Gaussian noise representative of Advanced LIGO sensitivity. We show th
at our network can classify signal from noise.\n\nhttps://agenda.infn.it/e
vent/15395/contributions/83821/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83821/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Search for gravitational wave transients in the second Advanced LI
GO and Virgo run
DTSTART;VALUE=DATE-TIME:20190220T171800Z
DTEND;VALUE=DATE-TIME:20190220T171900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83811@agenda.infn.it
DESCRIPTION:Speakers: Marco Drago (Istituto Nazionale di Fisica Nucleare)\
nThe second observing run of Advanced LIGO and Virgo ended on August 2017
with the detection of several coalescences. We report the results of a gen
eral search for gravitational waves of short duration using minimal assump
tion on the waveforms and sensitive to a wide range of sources. The analys
is includes the results of three different algorithms over the frequency f
rom 32 to 4096 Hz targeting signals with duration up to seconds. We will a
lso mention the results on the detected gravitational waves from coalescen
ces of compact object.\n\nhttps://agenda.infn.it/event/15395/contributions
/83811/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83811/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Spritz: a new fully general relativistic magnetohydrodynamic code
DTSTART;VALUE=DATE-TIME:20190220T164600Z
DTEND;VALUE=DATE-TIME:20190220T164700Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83813@agenda.infn.it
DESCRIPTION:Speakers: Federico Cipolletta (TIFPA - INFN)\nI will present f
ew initial steps towards a new general relativistic magneto hydrodynamic (
GRMHD) code devoted to the study of compact binary mergers with finite tem
perature equations of state and neutrino emission. Numerical modeling of n
eutron stars binaries (NS-NS)\, black holes binaries (BH-BH) and neutron s
tar black hole binaries (NS-BH) has now become one of the most important f
ields of study in theoretical astrophysics\, because it allows to extract
physical information from gravitational wave (GW) and electromagnetic sign
als by comparing simulated data with observations. Focusing on the NS-NS a
nd NS-BH cases in particular\, it has been shown many times that only a fu
lly general relativistic treatment taking also into account magnetic field
s may give a complete picture of this scenario and this requires to solve
the equations of GRMHD. From a numerical point of view\, one of the most d
emanding conditions imposed by the system of equations to be solved is the
so-called divergence-free condition for the magnetic field. In my work I
chose to consider the magnetic field coming out from a vector potential\,
in order to let the aforementioned conditions be automatically satisfied.
In addition\, I also consider a general treatment for the NS Equation Of S
tate (EOS) allowing for the use of finite temperature tabulated EOS. This
new code will also implement neutrino cooling in order to provide a more a
ccurate study of the post merger phase.\n\nhttps://agenda.infn.it/event/15
395/contributions/83813/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83813/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Disclosing the features of transient gravitational waves independe
ntly from waveform models
DTSTART;VALUE=DATE-TIME:20190220T171700Z
DTEND;VALUE=DATE-TIME:20190220T171800Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83814@agenda.infn.it
DESCRIPTION:Speakers: Claudia Lazzaro ()\nA very general reconstruction an
d estimation of the gravitational wave features\, i.e. not based on prior
knowledge of the waveform models\, is useful to catch unexpected character
istics of the signal. In addition\, it can complement the analyses based o
n parametrized models of the detected emissions from compact binary coales
cences. In fact\, we know that parametrized models may not always accurate
ly cover all the known possible variety of the emissions\, such as orbital
eccentricity\, misaligned spins and post-merger signals from neutron star
remnants. We will overview the un-modeled methods developed to characteri
ze the waveforms and the comparison with modeled analyses in the case of t
he LIGO-Virgo signal catalog GWTC-1.\n\nhttps://agenda.infn.it/event/15395
/contributions/83814/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83814/
END:VEVENT
BEGIN:VEVENT
SUMMARY:High-Precision Cosmology from the Sloan Digital Sky Survey Overtur
ns the ΛCDM Standard Model
DTSTART;VALUE=DATE-TIME:20190220T171600Z
DTEND;VALUE=DATE-TIME:20190220T171700Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83789@agenda.infn.it
DESCRIPTION:Speakers: Alexander Mayer (Independent Researcher)\nThe object
ive\, statistical nature of SDSS astrophysical datasets\, which were not d
riven by any theoretical agenda\, reveal false and misleading prior measur
ements (e.g.\, redshift-distance) driven by confirmation bias in the conte
xt of such agendas. SDSS theta-z\, redshift-magnitude (both spectroscopic
and photometric pipelines)\, and galaxy population-density data are shown
to conflict with the ΛCDM standard cosmological model. However\, all four
of these distinct and independent data sets are similarly consistent with
a new cosmological model. That new model\, which is consistent with Wille
m de Sitter’s exact solution to the Einstein field equations\, and which
derives from simple considerations of symmetry and local proper time mode
led as a geometric object\, motivated by Minkowski\, represents a major pa
radigm shift in cosmology. The canonical idea of a non-relativistic univer
sal time coordinate (i.e.\, ‘Cosmic time’ from initial singularity) is
supplanted by a relativistic\, strictly-local time coordinate involving n
o such unphysical singularity. The confrontation of all new predictive equ
ations\, having no free parameters\, with corresponding SDSS data sets def
initively resolves the modern quandary of ‘dark energy\,’ purported to
cause the improbable phenomenon of accelerating cosmic expansion.\n\nhttp
s://agenda.infn.it/event/15395/contributions/83789/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83789/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the interpretation of time
DTSTART;VALUE=DATE-TIME:20190220T171500Z
DTEND;VALUE=DATE-TIME:20190220T171600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83791@agenda.infn.it
DESCRIPTION:Speakers: Luigi Foschini (INAF Osservatorio Astronomico di Bre
ra)\nTime in physics is always viewed from the point of view of duration\,
but this interpretation causes many problems and paradoxes. I would like
to explore a change of interpretation of time. By thinking time as a cut\,
many problems could be easily solved. Particularly\, with such interpreta
tion\, quantum gravity theories based on 3+1 spacetime (e.g. Kuchar or Ell
is' evolving block universe) may open unexpected and fruitful views.\n\nRe
ferences: L. Foschini\, Fisica del Tempo (Bonomo\, Bologna\, 2018).\n\nhtt
ps://agenda.infn.it/event/15395/contributions/83791/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83791/
END:VEVENT
BEGIN:VEVENT
SUMMARY:General Poincar\\'e gauge theory: Hamiltonian structure and partic
le spectrum
DTSTART;VALUE=DATE-TIME:20190220T171400Z
DTEND;VALUE=DATE-TIME:20190220T171500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83792@agenda.infn.it
DESCRIPTION:Speakers: Branislav Cvetkovic (Institute of physics)\nBasic as
pects of the Hamiltonian structure of the parity-violating Poincar\\'e gau
ge theory are studied. We found all possible primary constraints\, identif
ied the corresponding critical parameters\, and constructed the generic fo
rm of the canonical Hamiltonian. In addition to being important in their o
wn right\, these results offer dynamical information that is essential for
a proper understanding of the particle spectrum of the theory\, calculate
d in the weak field approximation around the Minkowski background.\n\nhttp
s://agenda.infn.it/event/15395/contributions/83792/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83792/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The impact of the crust equation of state on the analysis of GW170
817
DTSTART;VALUE=DATE-TIME:20190220T171300Z
DTEND;VALUE=DATE-TIME:20190220T171400Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83793@agenda.infn.it
DESCRIPTION:Speakers: Rossella Gamba (Università di Torino e INFN sezione
di Torino)\nThe detection of GW170817\, the first neutron star-neutron st
ar merger observed by advanced LIGO and Virgo\, and its following analyses
represent the first contributions of gravitational wave data to understan
ding dense matter. Imposing a lower limit on the maximum mass value and pa
rametrizing the high density section of the equation of state of both neut
ron stars through spectral decomposition led to an estimate of the stars'
radii of $R_1 = 11.9_{- 1.4}^{+ 1.4}$ km and $R_2 = 11.9_{- 1.4}^{+ 1.4}$
km. These values do not\, however\, take into account the uncertainty owed
to the arbitrary choice of the crust low-density equation of state\, whic
h was fixed to reproduce the SLy equation of state model. We here re-analy
ze GW170817 data and establish that different crust models do not strongly
impact the mass or tidal deformability of a neutron star\, making it impo
ssible to distinguish between low density models through GW analysis. Howe
ver\, the crust does have an effect on radius. We predict the systematic e
rror due to this effect using neutron star structure equations\, and compa
re the prediction to results from full parameter estimation runs. For GW17
0817\, this systematic error affects the radius estimate by 0.3 km\, appro
ximately $3\\%$ of the neutron stars' radii.\n\nhttps://agenda.infn.it/eve
nt/15395/contributions/83793/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83793/
END:VEVENT
BEGIN:VEVENT
SUMMARY:About the measure of the bare cosmological constant
DTSTART;VALUE=DATE-TIME:20190220T171200Z
DTEND;VALUE=DATE-TIME:20190220T171300Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83873@agenda.infn.it
DESCRIPTION:Speakers: Massimo Cerdonio (INFN Section and University)\nI tr
y to revive\, and possibly reconcile\, a debate started a few years ago\,
about the relative roles of a bare cosmological constant and of a vacuum e
nergy\, by taking the attitude to try to get the most from the physics now
available as established. I take as starting point the proposals on how t
o regularize the particles vacuum energy without violating Lorentz invaria
nce. I notice that the bare cosmological constant of the Einstein equation
s\, which is there ever since GR emerged\, is actually constrained (if not
measured) indirectly from the effective cosmological constant observed no
w\, as given by CDM Precision Cosmology and from the cumulative vacuum
contribution of Standard Model\, SM\, particles\, when this is evaluated u
sing the well-established physics of Quantum Field Theory\, QFT. Therefore
the fine tuning\, implied by the compensation to a small positive value o
f the two large contributions\, could be seen as offered by Nature\, which
provides one more fundamental constant\, the bare Lambda. The possibility
is then discussed of constraining (measuring) directly such a bare cosmol
ogical constant by the features of primordial gravitational wave signals c
oming from hypothetical epoch’s precedent to the creation of particles.
A hint is briefly discussed for a possible bare Lambda inflation process.\
n\nhttps://agenda.infn.it/event/15395/contributions/83873/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83873/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the modified gravity and common nature of dark sector
DTSTART;VALUE=DATE-TIME:20190220T171100Z
DTEND;VALUE=DATE-TIME:20190220T171200Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83796@agenda.infn.it
DESCRIPTION:Speakers: A. Stepanian (A.I.Alikhanian National Laboratory)\nW
e show that (Eur Phys J C\, 2018)\, the gravity can be considered as defin
ed not by one but two fundamental constants which enables us to explain qu
antitatively both dark energy (the cosmological constant) in GR equations
and dark matter in weak-field limit simultaneously. Then\, in order to thr
ow more light on the nature of the constants appearing here\, we generaliz
e the Newton theorem on the 'sphere-point mass' equivalency to arbitrary d
imensions. We also turn into gravitational lensing\, where this additional
term predict a critical value for the involved weak-field parameter. If t
his value will be established at future observations\, this will mark the
first discrepancy with GR of the conventional weak-field limit\, directly
linked to the nature of the dark sector of the Universe.\n\nhttps://agenda
.infn.it/event/15395/contributions/83796/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83796/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Linear perturbations of an anisotropic Bianchi I model with a unif
orm magnetic field
DTSTART;VALUE=DATE-TIME:20190220T170900Z
DTEND;VALUE=DATE-TIME:20190220T171000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83797@agenda.infn.it
DESCRIPTION:Speakers: Federico Di Gioia (R)\nIn this work\, we study the e
ffect of a magnetic field on the growth of cosmological perturbations. We
develop a mathematical consistent treatment in which a perfect fluid and a
uniform magnetic field evolve together in a Bianchi I universe. We then s
tudy the energy density perturbations on this background with particular e
mphasis on the effect of the background magnetic field. We develop a solut
ion in the Newtonian treatment with adiabatic sound speed in the isotropic
limit. We also find the full relativistic anisotropic solution for pertur
bations in the directions parallel and perpendicular to the background mag
netic field when the sound speed is zero. This represents a new result in
GR since all the present studies deal with isotropic systems: our solution
s show a clear anisotropic behaviour and are far more complicated than the
FRW ones. We also write an equation for the general solution of the probl
em which could be numerically integrated.\n\nhttps://agenda.infn.it/event/
15395/contributions/83797/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83797/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Homogeneous AdS black strings in General Relativity and beyond
DTSTART;VALUE=DATE-TIME:20190220T171000Z
DTEND;VALUE=DATE-TIME:20190220T171100Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83799@agenda.infn.it
DESCRIPTION:Speakers: Adolfo Cisterna (Universidad Central de Chile)\nIn t
his talk we will present a new method to construct homogenous AdS black st
rings/p-branes in General Relativity and Lovelock gravity. These configura
tions are obtained by means of a specific "scalar dressing" of the extende
d coordinates. We will show how to use this method to construct the Schwar
zschild AdS black string\, the black string extension of the Boulware-Dese
r black hole and some black strings configurations in the presence of matt
er fields.\n\nhttps://agenda.infn.it/event/15395/contributions/83799/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83799/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Electromagnetic emission from axionic clouds
DTSTART;VALUE=DATE-TIME:20190220T170800Z
DTEND;VALUE=DATE-TIME:20190220T170900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83798@agenda.infn.it
DESCRIPTION:Speakers: Taishi Ikeda (Instituto Superior Técnico)\nAlthough
the existence of dark matter (DM) has been shown through various observat
ions\, nobody knows the identity of the DM. Axions were firstly introduced
to solve the strong CP problem\, and one of the possible candidate of DM.
\nDue to the super-radiance instability\, axion cloud is formed around Ker
r BHs.\nRecently\, it was suggested that once coupling to photons is consi
dered\, the laser of photons is emitted from the cloud through the couplin
g.\nIn this talk\, we solve numerically the Axion-Maxwell system\, and con
firm the existence of laser-like emission from clouds.\n\nhttps://agenda.i
nfn.it/event/15395/contributions/83798/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83798/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Parametrized 5.5PN accurate TaylorF2 approximant and its use in Pa
rameter Estimation
DTSTART;VALUE=DATE-TIME:20190220T170700Z
DTEND;VALUE=DATE-TIME:20190220T170800Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83802@agenda.infn.it
DESCRIPTION:Speakers: Francesco Messina (Istituto Nazionale di Fisica Nucl
eare)\nWe start from the state-of-the-art effective one-body (EOB) model a
nd suitably expand it up to 5.5PN order in the orbital (nonspinning) case.
\nBy comparing the so-obtained high-order PN phasing with the correspondi
ng EOB one\, we conclude that the 5.5PN approximation delivers a reliable
phasing description up to $M\\omega = 0.05$ for comparable mass binaries.
Although such cutoff frequency is reduced when the mass ratio is increased
\,the EOB/PN agreement is better with the 5.5PN approximant with respect t
o the standardly used 3.5PN one\, expecially at low frequencies. Beyond th
at\, an injection/recovery study is done. The injected waveforms are {\\tt
TEOBResumS} ones and we recover them using the TaylorF2 with a certain ti
dal part\, that can be either the 6PN one (leading order)\, or the NRTidal
one. We illustrate that the purely analytical point mass information is r
elevant in reducing the PE biases on the tidal parameters\, analyzing our
result for the Sly and h4 equations of state.\n\nhttps://agenda.infn.it/ev
ent/15395/contributions/83802/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83802/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Towards detailed comparison between effective-one-body models
DTSTART;VALUE=DATE-TIME:20190220T170600Z
DTEND;VALUE=DATE-TIME:20190220T170700Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83816@agenda.infn.it
DESCRIPTION:Speakers: Fabio Martinetti (Università di Torino e INFN sezio
ne di Torino)\nTEOBResumS and SEOBNR are the two mainstream analytical wav
eform models (informed by numerical-relativity information) that accuratel
y describe the dynamics of two coalescing compact objects of masses m1 and
m2 and spins S1 and S2 up to merger and ringdown. Both use the effective-
one-body (EOB) approach\, which maps the relative dynamics of two objects
into the dynamics of a (spinning) particle of mass mu=m1m2/(m1+m2) and spi
n moving in a deformed Kerr metric. In doing so\, the post-Newtonian expan
ded Hamiltonian is resummed in special ways so to improve its behavior and
its predictability in the strong-field\, fast-velocity regime up to merge
r. We compare in detail the analytical choices made in the two models\, fo
cusing in particular on the treatment of spin-orbit and spin-spin effects.
\n\nhttps://agenda.infn.it/event/15395/contributions/83816/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83816/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Calculation of gravitational constant in line with Wheeler idea on
gravitation
DTSTART;VALUE=DATE-TIME:20190220T170500Z
DTEND;VALUE=DATE-TIME:20190220T170600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83867@agenda.infn.it
DESCRIPTION:Speakers: Arban Uka (Epoka University)\nIt is widely accepted
that the general theory of relativity ceases to explain phenomena in the v
icinity and inside a black hole. Wheeler holds the idea that on the surfac
e of a Black hole the space parameters turn into quantum foam. He even con
templates on the geometry of space parameters as one zooms down on a point
particle. In this work we aim to solve challenges by employing a pair of
spacetime parameters of a quantum character. We call these of quantum char
acter because they are not experimentally measurable but provide a very us
eful relations between different physical quantities. This pair of spaceti
me parameters are linked together through the limiting quantity of space:
the Planck length. The realization of the idea of Wheeler helps to achieve
a beautiful connection between gravitation and electromagnetism\, an effo
rt on which Einstein worked for around 40 years. These steps respect the h
ierarchy of the physical quantities of energy\, momentum and force. This a
pproach respects the idea of Einstein who searched for a theory that had t
he concepts of the energy – or the field – at its center. The space pa
rameters are derived from a simple relation and are valid for the whole ra
nge of masses\, from the mass of the electron to the mass of the Universe.
From this relation the gravitational constant\, and the electrostatic for
ce are derived.\n\nhttps://agenda.infn.it/event/15395/contributions/83867/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83867/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravitational duality near cosmological scenarios
DTSTART;VALUE=DATE-TIME:20190220T170400Z
DTEND;VALUE=DATE-TIME:20190220T170500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83868@agenda.infn.it
DESCRIPTION:Speakers: Sergio Hörtner (Universidad Autonoma de Madrid)\nWe
shall present a SO(2) duality-symmetric form of the\nlinearized ADM actio
n principle when the linearization is performed on\nanti de Sitter and Kas
ner backgrounds. The analysis is based on the\ntwo-potential formalism\, o
btained upon resolution of the Hamiltonian\nconstraints\, and generalizes
previous works that focused on Minkowski\nand de Sitter backgrounds. The i
mplications of our results for\nholography and cosmology will be discussed
.\n\nhttps://agenda.infn.it/event/15395/contributions/83868/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83868/
END:VEVENT
BEGIN:VEVENT
SUMMARY:From fakeons to quantum gravity
DTSTART;VALUE=DATE-TIME:20190220T170300Z
DTEND;VALUE=DATE-TIME:20190220T170400Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83788@agenda.infn.it
DESCRIPTION:Speakers: Damiano Anselmi (PI)\nI introduce the concept of fak
e particle and study how it is used to formulate a consistent theory of qu
antum gravity. Fakeons arise from a new quantization prescription\, altern
ative to the Feynman one\, for the poles of higher-derivative theories\, w
hich avoids the problem of ghosts. The fake particles mediate interactions
and simulate true particles in many situations. Nevertheless\, they are n
ot asymptotic states and cannot be detected directly. The Wick rotation an
d the S matrix are regionwise analytic and the amplitudes can be calculate
d in all regions starting from the Euclidean one by means of an unambiguou
s\, but nonanalytic operation. By reconciling renormalizability and unitar
ity in higher-derivative theories\, the models containing both true and fa
ke particles are good candidates to explain quantum gravity. In pole posit
ion is the unique theory that is strictly renormalizable. One of the major
physical predictions due to the fakeons is the violation of microcausalit
y. I discuss the classical limit of the theory and the acausal corrections
to the Einstein equations.\n\nhttps://agenda.infn.it/event/15395/contribu
tions/83788/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83788/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Premetric telleparalel gravity and the geodesic principle.
DTSTART;VALUE=DATE-TIME:20190220T170200Z
DTEND;VALUE=DATE-TIME:20190220T170300Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83790@agenda.infn.it
DESCRIPTION:Speakers: Yakov Itin (The Hebrew University and Jerusalem Coll
ege of Technology)\nPremetric teleparallel gravity is a generalization of
GR based on two field equations similar to Maxwell’s equations of electr
odynamics. In gravitational model\, the scalar-valued 2-forms of electrody
namics are replaced by two vector-valued 2-forms. The energy-momentum 3-f
orm of matter and gravity field serves as a source. A general linear const
itutive relation between two basic fields provides a rich family of gravit
ational models. When this gravitational constitutive tensor is restricted
to a metric-dependent expression with a special choice of dimensionless pa
rameters\, the standard GR in its teleparallel equivalent version is recov
ered. The energy-momentum current and the Lorentz-type force density expre
ssions are defined for the whole family of models. They loss their invaria
nt meaning only when the construction is restricted to GR itself. It is be
cause of an additional local Lorentz transformation of frame field. We sho
w that this gravitational Lorentz force yields the proper geodesic equatio
n for the whole family of models (even including GR) when an additional me
chanical linear constitutive relation between the velocity and the momentu
m of a point-wise particle is assumed. This fact solves the known dichotom
y between geodesic and autoparallel trajectories in gravity models with a
general connection. \nReferences: \n1) Itin\, Y.\, Hehl\, F. W.\, & Obukh
ov\, Y. N. (2017). Premetric equivalent of general relativity: Teleparalle
lism. Physical Review D\, 95(8)\, 084020.\n2) Itin\, Y.\, Obukhov\, Y. N.\
, Boos\, J.\, & Hehl\, F. W. (2018). Premetric teleparallel theory of grav
ity and its local and linear constitutive law. The European Physical Journ
al C\, 78(11)\, 907.\n3) Itin\, Y. (2018). Premetric representation of mec
hanics\, electromagnetism and gravity. International Journal of Geometric
Methods in Modern Physics\, 1840002.\n\nhttps://agenda.infn.it/event/15395
/contributions/83790/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83790/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Factorization and resummation: A new paradigm to improve gravitati
onal wave amplitudes. II: the higher multipolar modes.
DTSTART;VALUE=DATE-TIME:20190220T170100Z
DTEND;VALUE=DATE-TIME:20190220T170200Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83800@agenda.infn.it
DESCRIPTION:Speakers: Messina Francesco (University of Milano Bicocca)\nWe
improve and generalize to all multipoles the factorization and resummatio
n approach of Nagar and Shah\,designed to improve the strong-field behavio
r of the post-Newtonian (PN) residual waveform amplitudes $f_{\\ell m}$'s
entering the effective-one-body\, circularized\, gravitational waveform fo
r spinning coalescing binaries. For a test-particle orbiting a Kerr black
hole\, each multipolar amplitude is truncate at relative 6~post Newtonian
(PN) order\, both for the orbital and spin factors. By taking a certain Pa
d\\'e approximant of the orbital factor in conjuction with the inverse Tay
lor (iResum) representation of the spin factor\, it is possible to push th
e analytical/numerical agreement of the energy flux at the level of $5\\%$
at the last-stable-orbit for a spinning black hole with dimensionless spi
n parameter $+0.99$.\n When the procedure is generalized to comparable-ma
ss binaries\, each orbital factor is\n kept at relative $3^{+3}$PN order\
, i.e. the globally 3PN-accurate comparable-mass terms\n are hybridized w
ith higher PN test-particle terms up to 6PN relative order in each mode.\n
The same Pad\\'e resummation is used for continuity. By contrast\, the s
pin factor is only\n kept at the highest comparable-mass PN-order current
ly available. We illustrate that the\n consistency between different trun
cations in the spin content of the waveform amplitudes\n is more marked i
n the resummed case than when using the standard Taylor-expanded form.\n
We finally introduce a method to consistently hybridize comparable-mass an
d test-particle\n information {\\it also} in the presence of spin.\n The
improved\, factorized and resummed\, multipolar waveform amplitudes prese
nted\n here are expected to set a new standard for effective-one-body-bas
ed\n gravitational waveform models.\n\nhttps://agenda.infn.it/event/15395
/contributions/83800/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83800/
END:VEVENT
BEGIN:VEVENT
SUMMARY:An improved analytical representation of the postmerger and ringdo
wn
DTSTART;VALUE=DATE-TIME:20190220T170000Z
DTEND;VALUE=DATE-TIME:20190220T170100Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83801@agenda.infn.it
DESCRIPTION:Speakers: Gunnar Riemenschneider (INFN sezione di Torino\, Uni
versitá degli studi di Torino)\nThe postmerger-ringdown waveform of coale
scing\, non-precessing\, spinning \nbinary black holes in the \\texttt{TEO
BresumS} model is given by a closed form\, analytic\, \ntime-domain family
of template waveforms\, informed by a large set of\nNumerical Relativity
waveforms from different codes such as the BAM code\, the SpEC code and \n
state-of-the-art test-particle waveforms. The NR waveforms cover the param
eter space\nfrom the equal mass case till the test-particle limit. This in
cludes 5 waveforms generated by the BAM\ncode with mass ratio $m_1/m_2=18$
and with the heavier BH spinning with spins up to $\\pm 0.8$.\nThe peak i
s fitted with an error of at most $2\\%$ in both amplitude and frequency.
The phase (amplitude) \nis fitted with an accuracy of at least $0.1rad$ ($
10\\%$) over the first 10-15M \nafter the peak\, with the exception of 3 o
utliers.\n\nStand alone the model can be used for several studies independ
ently as well.\nThe postmerger and ringdown of very heavy black hole binar
y systems\, \nsuch as GW170729\, will still be in the observable band of 2
nd generation \ngravitational wave detectors such as advanced LIGO and adv
anced Virgo.\nAnalyzing the signals directly in the time-domain\, using th
e analytical \npostmerger-ringdown waveform model\, gives a fully independ
ent \nmeasurement of source parameters. Further\, it was demonstrated in a
rXiv:1811.08744 that \nfits of key waveform characteristics\, such as peak
amplitude and frequency\, \ncould be used for consistency tests of genera
l relativity in the strong-field \nregime. \n\nAfter a pedagogical introdu
ction to the analytic setup I will discuss the \nset of Numerical Relativi
ty waveforms used to inform the model and highlight\nseveral technical det
ails of the fitting procedure. I will discuss the fitting of the\npeak str
uctures for the complex multipolar waveforms. I will conclude by showing\n
results of the application of the model to the analysis of real gravitatio
nal wave data.\n\nhttps://agenda.infn.it/event/15395/contributions/83801/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83801/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The cosmological impact of future constraints on $H_0$ from gravit
ational-wave standard sirens
DTSTART;VALUE=DATE-TIME:20190220T165900Z
DTEND;VALUE=DATE-TIME:20190220T170000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83803@agenda.infn.it
DESCRIPTION:Speakers: Fabrizio Renzi (Istituto Nazionale di Fisica Nuclear
e)\nGravitational-wave standard sirens present a novel approach for the de
termination of the Hubble constant. After the recent spectacular confirmat
ion of the method thanks to GW170817 and its optical counterpart\, additio
nal standard siren measurements from future gravitational-wave sources are
expected to constrain the Hubble constant to high accuracy. At the same t
ime\, improved constraints are expected from observations of cosmic microw
ave background (CMB) polarization and from baryon acoustic oscillations (B
AO) surveys. We explore the role of future standard siren constraints on $
H_0$ in light of expected CMB+BAO data. \nConsidering a $10$-parameters co
smological model\, in which curvature\, the dark energy equation of state\
, and the Hubble constant are unbounded by CMB observations\, we find that
a combination of future CMB+BAO data will constrain the Hubble parameter
to $\\sim 1.5 \\%$. Further extending the parameter space to a time-varyin
g dark energy equation of state\, we find that future CMB+BAO constraints
on $H_0$ are relaxed to $\\sim 3.0 \\%$. These accuracies are within reach
of future standard siren measurements from the Hanford-Livingston-Virgo a
nd the Hanford-Livingston-Virgo-Japan-India networks of interferometers\,
showing the cosmological relevance of these sources. If future gravitatio
nal-wave standard siren measurements reach $1\\%$ on $H_0$\, as expected\,
they would significantly improve future CMB+BAO constraints on curvature
and on the dark energy equation of state by up to a factor $\\sim 3$. We a
lso show that the inclusion of $H_0$ constraints from gravitational-wave s
tandard sirens could result in a reduction of the dark energy figure-of-me
rit (i.e.\, the cosmological parameter volume) by up to a factor of $\\sim
400$.\n\nhttps://agenda.infn.it/event/15395/contributions/83803/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83803/
END:VEVENT
BEGIN:VEVENT
SUMMARY:An almost-no-hair theorem for static spacetimes
DTSTART;VALUE=DATE-TIME:20190220T165800Z
DTEND;VALUE=DATE-TIME:20190220T165900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83808@agenda.infn.it
DESCRIPTION:Speakers: Raúl Carballo-Rubio (SISSA)\nThe simplicity of blac
k holes\, as characterized by no-hair theorems\, is one of the most import
ant mathematical results in the framework of general relativity. Are these
theorems unique to black hole spacetimes\, or do they also constrain the
geometry around regions of spacetime with arbitrarily large (although fini
te) redshift? In this talk I will discuss the answer to this question\, sh
owing how to extend Israel's theorem to static spacetimes without event ho
rizons that contain small deviations from spherical symmetry. This provide
s a first extension of no-hair theorems to ultracompact stars\, wormholes\
, and other exotic objects\, and paves the way for the construction of sim
ilar results for stationary spacetimes describing rotating objects.\n\nhtt
ps://agenda.infn.it/event/15395/contributions/83808/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83808/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Modified gravitational waves across galaxies from Macroscopic Grav
ity
DTSTART;VALUE=DATE-TIME:20190220T165700Z
DTEND;VALUE=DATE-TIME:20190220T165800Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83805@agenda.infn.it
DESCRIPTION:Speakers: Fabio Moretti (Sapienza)\nWe analyze the propagation
of gravitational \nwaves in a medium containing bounded \nsubsystems ("mo
lecules'')\, able to induce significant Macroscopic Gravity effects. We es
tablish a precise constitutive relation between the \naverage quadrupole a
nd the amplitudes of a vacuum gravitational wave\, via the geodesic deviat
ion equation. Then we determine\nthe modified equation for the wave inside
the medium and the associated dispersion relation. A phenomenological ana
lysis shows that \nanomalous polarizations of the wave emerge \nwith an ap
preciable experimental detectability \nif the medium is identified with a
typical galaxy. Both the modified dispersion relation \n(wave velocity les
s than the speed of light) \nand anomalous oscillations modes could be det
ectable by the incoming LISA or pulsar timing arrays experiments\, having
the appropriate size to see the concerned wavelengths\n(larger than the mo
lecular size) and \nthe appropriate sensitivity to detect the \nexpected d
eviation from vacuum General Relativity.\n\nhttps://agenda.infn.it/event/1
5395/contributions/83805/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83805/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum geometry of space-time from precanonical quantization of G
R
DTSTART;VALUE=DATE-TIME:20190220T165600Z
DTEND;VALUE=DATE-TIME:20190220T165700Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83850@agenda.infn.it
DESCRIPTION:Speakers: Igor Kanatchikov ()\nI review the approach of *preca
nonical quantization* based on the structures of the De Donder-Weyl Hamilt
onian formulation of field theories. The approach requires no splitting to
space and time and it leads to a new understanding of quantum fields as a
*hypercomplex* generalization of quantum theory rather than an infinite-d
imensional one. A relationship with the standard QFT in the *functional Sc
hroedinger representation*\, which emerges from precanonical quantization
as a singular limiting case\, is explained using the example of scalar fie
ld theory in flat and curved space-time. We apply the framework to the Pal
atini formulation of GR in vielbein and spin-connection variables and deri
ve the precanonical analogue of the Schroedinger equation for quantum grav
ity\, which is a PDE on the total space of the bundle of spin-connection c
oefficients over space-time. We discuss the Hilbert space in this formulat
ion\, the quantum gravitational avoidance of curvature singularities and t
he emergence of the Einstein equations in the classical limit. Using a sim
plified cosmological model we also show that the approach leads to a very
specific prediction of the Levy-type of statistics of quantum fluctuations
of spin-connection that may point to a fractal nature of quantum space-ti
me.\n\nhttps://agenda.infn.it/event/15395/contributions/83850/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83850/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kaluza-Klein and Nelson mechanisms reinterpreted on extended phase
-space for reconciling General Relativity with Quantum Mechanics
DTSTART;VALUE=DATE-TIME:20190220T165500Z
DTEND;VALUE=DATE-TIME:20190220T165600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83869@agenda.infn.it
DESCRIPTION:Speakers: claudio DI TROIA (ENEA)\nKaluza-Klein [1\,2] mechani
sm was rejected for inconsistencies due to the Planck length scale. \nNels
on [3] derivation of Quantum Mechanics was rejected for having assumed\, w
ithout justification\, a periodic multivalued action and the presence of u
niversal fluctuations. Both the mechanisms can be reinterpreted without pr
oblems at the light of the guiding center (for Kaluza-Klein) and gyrocente
r (for Nelson) transformations. It is demonstrated that with the use of gu
iding center coordinates the fields follow an Einstein’s equation on th
e phase-space extended to time and Gravitation includes electromagnetism i
f considered on such extended phase space. Once electromagnetic (now also
gravitational) fluctuations are considered it is shown that the gyrocenter
follows the Schroedinger equation. It is proposed to explaining the discr
epancies between GR and QM in the simplest way: they are describing differ
ent objects (guiding center and gyrocenter\, respectively) that are both r
epresentative of charges and/or masses. In this way a unified theory is a
ccessible and it can be depicted without inconsistencies [4]. \n[1] Kaluza
\, Th. (1921) Sitzungsberichte der Preussischen Akademie der Wissenschafte
nzu Berlin Math. Phys\, K1\, 374.\n[2] Klein\, O. (1926) Zeitschrift für
Physik\, 37\, 895-906. \nhttps://doi.org/10.1007/BF01397481\n[3] Nelson\,
E. (1966) Physical Review\, 150\, 1079. \nhttps://doi.org/10.1103/PhysRev
.150.1079\n[4] Di Troia\, C (2018) Journal of Modern Physics\, 9\, 701\n\n
https://agenda.infn.it/event/15395/contributions/83869/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83869/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravitational Radiation from chirping compact stars and inspiral p
lanets around intermediate-mass black-holes: detection degeneracy
DTSTART;VALUE=DATE-TIME:20190220T165400Z
DTEND;VALUE=DATE-TIME:20190220T165500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83864@agenda.infn.it
DESCRIPTION:Speakers: Jose Fernando Rodriguez-Ruiz (Icranet-Icra Universit
y of Rome "La sapienza")\nWe show that compressible\, Riemann-S type ellip
soids can emit gravitational waves (GWs) with a chirp-like structure (chir
ping ellipsoids\, CELs). The potential detection of these type of sources
with eLISA and other future space-based GW observatories can reveal previo
usly undetected astrophysical processes in system of compact objects (e.g.
the postmerger object of white dwarf binary mergers). We study the intri
nsic phase-time evolution and the fourier transform\, in order to demonstr
ate that the waveform of CELs (mass $\\sim1$~M$_\\odot$\, radius $\\sim10^
3$~km\, polytropic equation of state with index $n\\approx 3$) is almost
indistinguishable from that emitted by extreme mass-ratio inspirals (EMRIs
) composed of an intermediate-mass (e.g.~$10^3~M_\\odot$) black hole and a
planet-like (e.g.~$10^{-4}~M_\\odot$) companion. In addition\, the miss-m
atch between the two waveforms is computed and we show that for one year o
f observation\, they are almost indistinguishable. The detection of these
EMRIs is relevant for the understanding of planetary formation and dynamic
s in crowded stellar systems. From reasonable astrophysical assumptions\,
the rate in the local Universe of CEL and EMRIs in the mass range conside
red here\, are very similar.\n\nhttps://agenda.infn.it/event/15395/contrib
utions/83864/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83864/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Open Quantum Theory of two Entangled Atoms in De-Sitter Space
DTSTART;VALUE=DATE-TIME:20190220T165300Z
DTEND;VALUE=DATE-TIME:20190220T165400Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83841@agenda.infn.it
DESCRIPTION:Speakers: Choudhury (Max Planck Institute for Gravitational Ph
ysics\, Potsdam.)\nIn this paper\, our prime objective is to investigate t
he thermal nature of the de- Sitter space generated due to the entanglemen
t between a pair of Unruh-De-Witt detectors in the paradigm of open quantu
m systems. The Master-equation of pair of a two-level atomic system within
a framework of weakly interacting limit in the de-Sitter space is solved.
One of the most important phenomena occurring due to the vacuum-fluctuati
ons of a conformally coupled scalar field is the Casimir effect is studied
in the framework of open quantum systems with a weakly-interacting enviro
nment degrees of freedom. Such vacuum fluctuations enhance the entanglemen
t between the two atoms thereby resulting in the thermalization of the spa
ce-time and encodes the Unruh Effect into it. We study how the Resonance C
asimir- Polder interaction between the two atoms manifests the curvature o
f space-time. Another main objective of this paper is to investigate the a
symptotic entanglement between the two atoms giving rise to an ensemble of
thermal states encoded within the vacuum state of the scalar field. These
thermal phenomena is obtained by the Gibbons-Hawking temperature is widel
y studied with respect to various toy model Hamiltonian for an entangled p
air of atoms weakly conformally coupled to a scalar field.\n\nhttps://agen
da.infn.it/event/15395/contributions/83841/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83841/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A quantum low-energy gravity model free from causality violation p
roblems
DTSTART;VALUE=DATE-TIME:20190220T165200Z
DTEND;VALUE=DATE-TIME:20190220T165300Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83830@agenda.infn.it
DESCRIPTION:Speakers: Adele Naddeo (INFN\, Sezione di Napoli)\nWave-functi
on collapse following a measurement process is a longstanding controversia
l issue of quantum physics. It introduces an element of strong non-lineari
ty and irreversibility in an otherwise unitary and reversible dynamics. Se
veral proposals of modification of Quantum Mechanics have been put forward
in the past few decades in order to solve such a dichotomy. Among them\,
some approaches considered the possible role of gravity in the wave-functi
on collapse as a result of the incompatibility of general relativity and u
nitary time evolution of Quantum Mechanics. In this contribution we presen
t a nonunitary model of Newtonian Gravity (NNG) [1-3]\, which shows severa
l appealing features: while reproducing at a macroscopic level the ordinar
y Newtonian interaction\, it presents a mass threshold for gravitational l
ocalization. In particular\, it provides a mechanism for the evolution of
macroscopic coherent superpositions of states into ensembles of pure state
s.\nIn particular\, we explicitly show how a one-parameter generalization
of our NNG model is free from any causality-violation problem for any fini
te value of parameter [4]. The basic idea is to look at the single particl
e Newton-Schroedinger equation as the mean-field approximation of an equat
ion of N identical copies of the particle\, interacting via usual gravitat
ional interaction\, when N goes to infinity. The general N-copy model is a
fully consistent quantum theory\, in which superluminal communications ar
e automatically avoided. This feature is shown to be a consequence of the
intrinsic mechanism of spontaneous state reduction\, built in in our NNG m
odel and completely suppressed in the Newton-Schroedinger limit. We discus
s in detail a specific (ideal) EPR-like experiment involving the superposi
tion of two distinct Center of Mass position states of a massive body and
show that the absence of causality violations leads to the appearance of u
nusual communications among Everett branches of the wave function. Our res
ults agree with previous findings by Polchinski [5]\, obtained for a gener
al class of nonlinear models characterized by nonlinear observables which
depend only on the density matrix.\n\nReferences\n[1] S. De Filippo\, F. M
aimone\, Phys. Rev. D 66\, 044018 (2002).\n[2] F. Maimone\, G. Scelza\, A.
Naddeo\, V. Pelino\, Phys. Rev. A 83\, 062124 (2011).\n[3] G. Scelza\, F.
Maimone\, A. Naddeo\, J. Phys. Comm. 2\, 015014 (2018).\n[4] F. Maimone\,
G. Scelza\, A. Naddeo\, arXiv:1809.08653.\n[5] J. Polchinski\, Phys. Rev.
Lett. 66\, 397 (1991).\n\nhttps://agenda.infn.it/event/15395/contribution
s/83830/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83830/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Post-adiabatic approximation for gravitational wave inspirals
DTSTART;VALUE=DATE-TIME:20190220T165100Z
DTEND;VALUE=DATE-TIME:20190220T165200Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83810@agenda.infn.it
DESCRIPTION:Speakers: Piero Rettegno (Università di Torino e INFN sezione
di Torino)\nThe most accurate semi-analytical models for gravitational wa
ve models for compact binaries are based on the effective-one-body (EOB) a
pproach and calibrated to numerical relativity (NR) simulations. These mod
els are however too slow to be used in parameter estimation runs\, when $\
\sim 10^7$ waveforms have to be generated. This has prompted the construct
ion of surrogate models\, based on the reduced-order modeling (ROM) techni
que\, in order to shorten the waveform evaluation time.\nThe post-adiabati
c approximation is used in state of the art EOB-NR models to generate init
ial conditions with low eccentricity. In [arxiv:1805.03891][1]\, this appr
oximation has been extended and used to determine the complete dynamics of
the binary system. This avoids the numerical solution of two of the four
Hamilton's equations (for non-precessing systems)\, which constitutes the
main contribution to the waveform computation cost.\nIn practice\, one can
analytically compute the momenta of the system at any given radius\, unde
r the approximation that the gravitational wave flux is small. The time an
d orbital phase are then recovered by means of numerical quadratures on a
very sparse grid. In the regime where this approximation is no longer vali
d (tipically the last few orbits)\, it can be used to generate the initial
conditions of the ordinary dynamics as done usually. \nUsing this approac
h\, it is possible to evaluate a binary neutron star waveform from 10 Hz i
n 50 milliseconds\, with respect to the $\\sim 1$ second that we obtain nu
merically solving the four ordinary differential equations (these times re
fer to the [TEOBResumS][2] model). Even when this time-domain waveform is
interpolated (using the standard GLS interpolator) on a uniform-in-time gr
id\, the evaluation times become 0.37 and 1.7 seconds respectively.\nThe u
se of the post-adiabatic approximation hence drastically reduces the compu
tational cost of EOB-NR models while retaining their full flexibility. Thi
s makes it possible to directly use the best available semi-analytical mod
els in parameter estimation runs and\, above all\, tests of general relati
vity.\nThis approach should be adaptable to the case of eccentric binaries
and would be of certain use for extreme mass ratio inspirals that will be
detected by LISA. \n \n\n\n [1]: https://arxiv.org/abs/1805.03891\n [2]
: https://bitbucket.org/eob_ihes/teobresums\n\nhttps://agenda.infn.it/even
t/15395/contributions/83810/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83810/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Compact objects and the swampland
DTSTART;VALUE=DATE-TIME:20190220T165000Z
DTEND;VALUE=DATE-TIME:20190220T165100Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83822@agenda.infn.it
DESCRIPTION:Speakers: Kunihito Uzawa (Kwansei Gakuin University)\nRecently
\, two simple criteria were proposed to assess if vacua emerging from an e
ffective scalar field theory are part of the string "landscape" or "swampl
and". The former are the vacua that emerge from string compactifications\;
the latter are not obtained by any such compactification and hence may no
t survive in a UV completed theory of gravity. So far\, these criteria hav
e been applied to inflationary and dark energy models. Here we consider th
em in the context of solitonic compact objects made up of scalar fields: b
oson stars. Analysing several models (static\, rotating\, with and without
self-interactions)\, we find that\, in this context\, the criteria are no
t independent. Furthermore\, we find the universal behaviour that in the r
egion wherein the boson stars are expected to be perturbatively stable\, t
he compact objects may be part of the landscape. By contrast\, in the regi
on where they may be faithful black hole mimickers\, in the sense they pos
sess a light ring\, the criteria fail (are obeyed) for static (rotating) u
ltracompact boson stars\, which should thus be part of the swampland (land
scape). We also consider hairy black holes interpolating between these bos
on stars and the Kerr solution and establish the part of the domain of exi
stence where the swampland criteria are violated. In interpreting these re
sults one should bear in mind\, however\, that the swampland criteria are
not quantitatively strict.\n\nhttps://agenda.infn.it/event/15395/contribut
ions/83822/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83822/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Parametric instabilities predictions for Advanced Virgo
DTSTART;VALUE=DATE-TIME:20190220T164500Z
DTEND;VALUE=DATE-TIME:20190220T164600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83818@agenda.infn.it
DESCRIPTION:Speakers: Thibaut Jacqmin (Laboratoire Kastler Brossel/Sorbonn
e University)\nNow that gravitational waves from compact binary coalescenc
es have been successfully detected by the global LIGO-Virgo network\, a ke
y challenge is to improve the detector sensitivity in order to detect more
transient sources — weaker or located further away. The detectors' sens
itivity can be enhanced by increasing the laser power travelling within th
e arm cavities\, for it reduces the effect of the laser quantum phase nois
e\, which is the fundamental noise that dominates the sensitivity in the h
igh-frequency range (above a few hundreds of Hz). However\, a nonlinear op
tomechanical phenomenon that has long been studied\, and which is called p
arametric instabilities (PI)\, may limit the amount of energy stored in th
e Fabry-Perot resonator\, and thus the laser power.\nPI comes from the cou
pling of three modes: a mirror mechanical mode (MM) that sets the mirror s
urface in motion\, the fundamental optical mode of an optical cavity (TEM0
0)\, and a higher order optical mode (HOM). Photons scattering from the TE
M00 to a HOM can generate an optical beat note if the difference in freque
ncies of the two optical modes is equal to the MM resonance frequency. Thi
s beat note\, in turn\, can either damp or increase the mechanical motion
via radiation pressure. The latter effect could lead to an excitation\, th
at is\, first exponentially growing\, and then reaches a plateau after som
e time. The signal associated with this mirror excitation would be aliasin
g in the detection band\, thus saturating the electronics.\nIn 2015\, duri
ng the Observing Run 1 (O1)\, LIGO observed PIs when a mirror mechanical m
ode at 15 kHz became unstable\, for an intracavity power of 50 kW. That is
why we study the effects of PIs for the Virgo configuration with various
parameters in order to scan PIs around theoretical and computed values so
that we could take hypothetical errors into account. We\, as well\, compar
e results using perfect spherical maps and measured mirror maps. Alongside
with which we study the effects of optical losses that can counterintuiti
vely increase the parametric gain. Finally\, we show that the O3 nominal i
ntracavity power of 272 kW\, could bring from zero to a few tens of unstab
le modes\, depending on the radii of curvatures of the mirrors\, if all th
e mechanical modes quality factors are assumed to be equal to 10^7.\n\nhtt
ps://agenda.infn.it/event/15395/contributions/83818/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83818/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Low Latency gravitational alerts of the LIGO/Virgo collaboration
DTSTART;VALUE=DATE-TIME:20190220T164900Z
DTEND;VALUE=DATE-TIME:20190220T165000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83827@agenda.infn.it
DESCRIPTION:Speakers: Sarah Antier ()\nThe second LIGO-Virgo observational
witnessed the birth of gravitational-wave multi-messenger astronomy. The
first ever gravitational-wave (GW) detection from the coalescence of two n
eutron stars\, GW170817\, associated to its gamma-ray counterpart\, GRB 17
0817A\, as well as its optical\, X-ray and radio counterparts (AT 2017gfo)
.\n\nIn this talk\, we will describe the O2 low-latency program of the LIG
O/Virgo collaboration\, enabling multi-messenger discovery. We will focus
on the online candidate alerts shared with observing partners during O2. F
irst\, we will describe the distribution of gravitational-wave alerts : we
will highlight the validation process\, especially from the detector char
acterization effort to separate transient noise from real GW signal. We wi
ll also show the gravitational-wave observables which were sent in the ale
rts to enable searches for their counterparts.\n\nThe next observation cam
paign O3 (starting coming Spring) promises multiple GW detections: the exp
ected rate of binary black hole (BBH) triggers will be around one every fe
w days whereas binary neutron stars rate is estimated to be one every two
weeks at most. The LIGO-Virgo Collaboration (LVC) has developed a robust a
lert system for the open public alerts (OPA) era in order to enable a prom
pt electromagnetic follow-up. This requires some automations as: selection
of the best GW trigger candidate among the different online searches and
the validation process to reject transients originated from the noise. Thi
s talk will present as a second part an overview of the O3 LIGO-Virgo low-
latency multi-messenger program.\n\nhttps://agenda.infn.it/event/15395/con
tributions/83827/
LOCATION:Phys. Dept. Marconi I Floor
URL:https://agenda.infn.it/event/15395/contributions/83827/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nonlocal quantum field theories
DTSTART;VALUE=DATE-TIME:20190220T101500Z
DTEND;VALUE=DATE-TIME:20190220T103200Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83795@agenda.infn.it
DESCRIPTION:Speakers: Fabio Briscese (SUSTech)\nIt has been realized that
nonlocality might be a key ingredient for the formulation of a quantum ren
ormalizable theory of gravitation. In facts\, nonlocal gravitational model
s are earning growing interest in the scientific community\, since they ar
e super-renormalizable or even finite at quantum level. In this seminar I
will introduce nonlocal field theories and discuss their general features.
In particular\, I will discuss power counting renormalization and finiten
ess. Moreover\, I will show how Cutkosky rules are generalized to the case
of nonlocal theories\, so that the perturbative unitarity is easily estab
lished. Finally\, I will discuss the problem of causality in nonlocal theo
ries.\n\nhttps://agenda.infn.it/event/15395/contributions/83795/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83795/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Status of TEOBResumS
DTSTART;VALUE=DATE-TIME:20190219T112600Z
DTEND;VALUE=DATE-TIME:20190219T114300Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83765@agenda.infn.it
DESCRIPTION:Speakers: Alessandro Nagar (INFN sezione di Torino\, Centro Fe
rmi and IHES)\nI will review the status of TEOBResumS\, that is a state of
the art effective-one-body based waveform model for spin-aligned coalesci
ng compact binaries\, e.g. black hole binaries and neutron star binaries.
I will focus on the impact of the numerical relativity information needed
to complete the analytical model and focus on the performance of the model
for gravitational wave data-analytsis purposes.\n\nhttps://agenda.infn.it
/event/15395/contributions/83765/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83765/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Metric properties of ‘rigor mortis’ accelerations—Born’s
‘rigid motion’ collinear scenarios—without Minkowski spacetime
DTSTART;VALUE=DATE-TIME:20190219T114300Z
DTEND;VALUE=DATE-TIME:20190219T120000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83766@agenda.infn.it
DESCRIPTION:Speakers: Brian Coleman (BC Systems (Erlangen))\nAn extended a
ccelerating body under ‘rigid motion’ by definition manifests unvaryin
g separation between its constituents in all comoving inertial frames. Rel
ationships be- tween constituents’ necessarily di↵ering yet constant a
ccelerations—reflecting a nonuni- form\, dynamically changing and moreov
er repulsive gravitational field—have been es- tablished by Woodhouse in
2003 using Minkowski spacetime\, by Franklin in 2010 using Lorentz transf
ormations\, and by the present author in 2013 using unfamiliar yet simple
inter-rocket radar period equations. A second ‘pseudo-rigor mortis’ at
tractive gravita- tional field scenario introduced in 2018 is now further
considered. In both cases\, radar trajectories are shown to exhibit unchan
ging inverse square root of two geodesic curvature on a corresponding real
-metric spacetime surface of ubiquitously zero Gauss curvature.\nKeywords:
spacetime metric\; own-surface\; hemix\; rigor mortis motion\; radar path
s\; geodesics\; Gauss curvature\; gravitational fields.\n\nhttps://agenda.
infn.it/event/15395/contributions/83766/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83766/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Measurements of the PPN parameters with radio links in the space
DTSTART;VALUE=DATE-TIME:20190220T141000Z
DTEND;VALUE=DATE-TIME:20190220T144500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84042@agenda.infn.it
DESCRIPTION:Speakers: Luciano Iess (University of Rome Sapienza)\nhttps://
agenda.infn.it/event/15395/contributions/84042/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84042/
END:VEVENT
BEGIN:VEVENT
SUMMARY:GW and Pulsar timing with PTA/SKA
DTSTART;VALUE=DATE-TIME:20190221T091000Z
DTEND;VALUE=DATE-TIME:20190221T094500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84040@agenda.infn.it
DESCRIPTION:Speakers: Possenti Andrea (INAF Cagliari)\nhttps://agenda.infn
.it/event/15395/contributions/84040/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84040/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Relativistic effects in stellar orbits and gas around the Galactic
Center black hole
DTSTART;VALUE=DATE-TIME:20190221T105600Z
DTEND;VALUE=DATE-TIME:20190221T111300Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83770@agenda.infn.it
DESCRIPTION:Speakers: Odele Straub (Max Planck Institute for Extraterrestr
ial Physics)\nThe supermassive black hole in the center of our galaxy is t
he closest of its kind and the largest in the sky. It is surrounded by a s
mall cluster of high velocity stars called S-stars. Their trajectories are
governed by the gravitational field of the black hole. We used the Very L
arge Telescope (VLT) instruments GRAVITY and SINFONI to follow the star S2
/S-02 during its pericenter passage\, collecting astrometric and spectrosc
opic data\, respectively. These joint data allow a now robust detection of
the combined gravitational redshift and transverse Doppler effect for S2/
S-02. During high emission states (bright flares)\, GRAVITY also recorded
continuous changes in position and polarisation of the IR source Sgr A* it
self. These are attributed to a compact source of synchrotron emission (ho
t spot) from the innermost stable circular orbit around the black hole. I
will discuss how we obtained our recent result and what it means in the co
ntext of gravity theories.\n\nhttps://agenda.infn.it/event/15395/contribut
ions/83770/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83770/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phenomenological aspects of black holes beyond general relativity
DTSTART;VALUE=DATE-TIME:20190221T100500Z
DTEND;VALUE=DATE-TIME:20190221T102200Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83773@agenda.infn.it
DESCRIPTION:Speakers: Stefano Liberati (TS)\nBlack holes comprise a remark
ably elegant set of solutions of the Einstein field equations. Aside from
their rich mathematical structure\, they are nowadays accepted as legitima
te astrophysical objects and are routinely used in order to explain astrop
hysical observations. Nonetheless\, General Relativity black holes were fo
r a long time regarded with skepticism by many\, even Einstein himself\, a
s they imply infinite curvatures at their core (singularities) as well as
infinite redshift at the horizon. What if nature tames somehow such infini
ties? How could we distinguish such “regularised black holes” from the
standard ones? In this talk I shall try to present an overview of possibi
lities and their possible phenomenology with a specific attention at what
could be observationally done in the near and far future.\n\nhttps://agend
a.infn.it/event/15395/contributions/83773/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83773/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anisotropies in the stochastic gravitational-wave background
DTSTART;VALUE=DATE-TIME:20190220T151000Z
DTEND;VALUE=DATE-TIME:20190220T152700Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83782@agenda.infn.it
DESCRIPTION:Speakers: Alexander Jenkins (King's College London)\nIn the ne
w era of gravitational-wave astronomy\, one of the most exciting targets f
or future observations is the stochastic gravitational-wave background (SG
WB). While we have yet to detect the SGWB\, we expect that by studying the
angular power spectrum of its anisotropies\, we may learn about the large
-scale structure of the Universe (analogous to studies of the CMB). With t
his in mind\, we develop detailed models of the SGWB anisotropies from two
important sources of gravitational waves: unresolved compact binary coale
scences\, and cosmic strings.\n\nhttps://agenda.infn.it/event/15395/contri
butions/83782/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83782/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Loop Quantum Gravity: Planckian discreteness of spacetime geometry
and possible implications.
DTSTART;VALUE=DATE-TIME:20190219T094000Z
DTEND;VALUE=DATE-TIME:20190219T101500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84014@agenda.infn.it
DESCRIPTION:Speakers: Alejandro Perez (Aix-Marseille University)\nhttps://
agenda.infn.it/event/15395/contributions/84014/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84014/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Measuring the galactic gravito-magnetism on Earth
DTSTART;VALUE=DATE-TIME:20190221T102200Z
DTEND;VALUE=DATE-TIME:20190221T103900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83783@agenda.infn.it
DESCRIPTION:Speakers: Angelo Tartaglia (INAF and Politecnico di Torino)\nG
eneral Relativity tells us that that a spinning source of gravity produces
\, in weak field approximation\, both an attractive Newton-like force and
a gravito-magnetic interaction. This is of course true for the whole Milk
y Way and in particular for its dark halo\, if it exists. Here I discuss t
he opportunity of putting upper limits to the intensity of a possible gala
ctic gravito-magnetic field\, by terrestrial experiments. When a gravito-m
agnetic field concatenates with a loop closed in the space of a given obse
rver\, it causes a difference in the time of flight of right- and left-han
ded electromagnetic signals along that loop: this is the generalized versi
on of the Sagnac effect\, combining kinematical rotations and general rela
tivity. Terrestrial devices exploiting this effect are for instance ring l
asers. A galactic gravito-magnetic field would practically be constant in
the whole internal solar system\, but a ring fixed on the surface of the e
arth at a given latitude would daily oscillate its normal with respect to
the axis of the Milky Way by an angular amplitude as big as the latitude.
This diurnal (stellar day) modulation would be a possible footprint of the
galactic gravito-magnetic interaction.\n\nhttps://agenda.infn.it/event/15
395/contributions/83783/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83783/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Graceful Exit for the Cosmological Constant Damping Scenario
DTSTART;VALUE=DATE-TIME:20190221T111300Z
DTEND;VALUE=DATE-TIME:20190221T113000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83784@agenda.infn.it
DESCRIPTION:Speakers: Kévin Nguyen (Vrije Universiteit Brussel)\nAbstract
: I will present a simple and generic class of scalar-tensor theories that
successfully realize dynamical damping of the effective cosmological cons
tant\, therefore providing a viable dynamical resolution of the fine-tunin
g cosmological constant problem. In contrast to early versions of this app
roach\, the models considered do not suffer from unacceptable variations o
f Newton's constant\, as one aims at a small but strictly positive late-ti
me curvature. I will then show that the original fine-tuning issue is trad
ed for a hierarchy of couplings\, and further suggest a way to naturally g
enerate this hierarchy based on fermion condensation and softly broken fie
ld shift symmetry. This talk is based on Phys. Rev. D 98\, 124031 (2018)\,
arXiv:1810.12336.\n\nhttps://agenda.infn.it/event/15395/contributions/837
84/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83784/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Testing Gravity with pulsars at the Galactic Center
DTSTART;VALUE=DATE-TIME:20190221T103900Z
DTEND;VALUE=DATE-TIME:20190221T105600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83785@agenda.infn.it
DESCRIPTION:Speakers: Mariafelicia De Laurentis (Università di Napoli Fed
erico II)\nTo date\, the most precise tests of General Relativity have bee
n achieved\nthrough pulsar timing\, albeit in the weak-field regime. Since
pulsars are\nsome of the most precise and stable "clocks" in the Universe
\, present\nobservational efforts are focused on detecting pulsars in the
vicinity of\nsupermassive black holes (most notably in the Galactic Centre
)\, enabling\npulsar timing to be used as an extremely precise probe of st
rong-gravity\nregime.\nIn this work\, test-particle dynamics is described
in general black-hole\nspacetimes and used to study binary systems comp
rising a pulsar orbiting\na black hole. It is shown that\, by adopting a f
ully general-relativistic\ndescription of test-particle motion\, independe
nt of any particular theory\nof gravity\, observations of pulsars give re
liable constraints on \nalternative theories of gravity.\n\nhttps://agend
a.infn.it/event/15395/contributions/83785/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83785/
END:VEVENT
BEGIN:VEVENT
SUMMARY:MICROSCOPE: while waiting for the final results
DTSTART;VALUE=DATE-TIME:20190221T083500Z
DTEND;VALUE=DATE-TIME:20190221T091000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83831@agenda.infn.it
DESCRIPTION:Speakers: Joel Bergé (ONERA / Paris Saclay University)\nMICRO
SCOPE is a CNES-ESA-DLR-ONERA-CNRS-OCA-ZARM space mission that aimed to te
st the Weak Equivalence Principle (WEP) at the $10^{-15}$ level\, i.e. two
orders of magnitude better than the best "pre-MICROSCOPE" on-ground tests
. The WEP is the cornerstone of General Relativity\, the postulate that le
d Einstein to establish his theory: it states that all bodies fall at the
same rate\, independently of their mass and composition. Alternative theor
ies of gravity\, like those developed to overcome such conundrums as dark
energy or the unification of gravity with the forces of the standard model
of particle physics\, generically predict a small violation of the WEP. A
s a consequence\, not only does MICROSCOPE test the very foundation of Gen
eral Relativity\, but it also provides new constraints on theories beyond
Einstein's.\n\nLaunched on April 25\, 2016\, the MICROSCOPE satellite and
its scientific instruments provided high-quality data during the entire mi
ssion\, which came to its end on October 16\, 2018. The first results\, ba
sed on 7% of the total data\, ruled out a violation of the WEP greater tha
n $2\\times10^{-14}$. Since then\, more data have been taken and additiona
l analyses have been conducted to better constrain the level of systemati
c errors. While the remaining data is still being analysed\, the final MIC
ROSCOPE results should come closer to the $10^{-15}$ precision\; they shou
ld be published at the end of 2019.\n\nIn this talk\, I will first introdu
ce the MICROSCOPE mission\, in particular its scientific goals and measure
ment principles. Then\, I will discuss its first results and mention what
constraints MICROSCOPE can bring on some modified gravity models.\n\nhttps
://agenda.infn.it/event/15395/contributions/83831/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83831/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dark energyy and weak lensing
DTSTART;VALUE=DATE-TIME:20190221T080000Z
DTEND;VALUE=DATE-TIME:20190221T083500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84041@agenda.infn.it
DESCRIPTION:Speakers: Hendrik Hildebrandt (University of Bonn)\nhttps://ag
enda.infn.it/event/15395/contributions/84041/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84041/
END:VEVENT
BEGIN:VEVENT
SUMMARY:What neutron star mergers and their gravitational wave signal can
teach us about matter under extreme conditions
DTSTART;VALUE=DATE-TIME:20190220T160100Z
DTEND;VALUE=DATE-TIME:20190220T161800Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83781@agenda.infn.it
DESCRIPTION:Speakers: Elias Roland Most (Goethe University Frankfurt)\nWit
h the detection of GW170817 we have observed the first multi messenger sig
nal from two merging neutron stars.\n\nThis signal carried a multitude of
information about the underlying equation of state(EOS) of nuclear matter\
, which so far is not known for densities above nuclear saturation.\nIn pa
rticular it is not known if exotic states or even a phase transition to qu
ark matter can occur at densities so extreme that they can't be probed by
any current experiment.\n\nI will show how the information carried in the
gravitational wave signal of GW170817 can be used to constrain the EOS at
densities above saturation and what we can learn about the possible existe
nce of phase transitions.\nI will also comment on how we can use future gr
avitational wave detections in order to set limits on the existence of neu
tron stars having a quark matter core.\n\nFinally\, I will discuss the det
ectability of a quark-hadron phase transition taking place in a neutron st
ar merger event.\n\nhttps://agenda.infn.it/event/15395/contributions/83781
/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83781/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A method for directed searches of continuous gravitational waves i
n advanced detector data
DTSTART;VALUE=DATE-TIME:20190220T154400Z
DTEND;VALUE=DATE-TIME:20190220T160100Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83779@agenda.infn.it
DESCRIPTION:Speakers: Ornella Juliana Piccinni (INFN - Sapienza)\nContinuo
us waves (CW) are still undetected gravitational wave signals emitted by r
otating neutron stars\, isolated or in binary systems. The estimated numbe
r of isolated neutron stars in our Galaxy is 10^8-10^9. Information provid
ed by electromagnetic observations is crucial to constrain the signal para
meter space\, lower the computational cost of a CW search and increase the
number of potential targets. Accordingly to the information available abo
ut the source\, different searches can be set up.\nIn this work we present
prospects for the directed search of CW signals in advanced LIGO-Virgo da
ta using the BSD-directed search method. A list of potentially interesting
sources\, which are present in the main astronomical catalogues\, along w
ith some young supernova remnants\, is investigated and theoretical indire
ct upper limits are computed when possible. Estimate of the computational
power needed to perform a directed search for the selected sources is also
provided.\n\nhttps://agenda.infn.it/event/15395/contributions/83779/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83779/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravitational waves in massive gravity: waveforms from extreme-mas
s-ratio mergers
DTSTART;VALUE=DATE-TIME:20190220T161800Z
DTEND;VALUE=DATE-TIME:20190220T163500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83777@agenda.infn.it
DESCRIPTION:Speakers: Andrea Maselli (Sapienza University of Rome)\nPrecis
ion tests of the strong gravity regime through direct observations of grav
itational wave events\, will provide new crucial insights on the nature of
gravity. In this regard\, a long lasting questions that has survived one
century of investigation\, is wether the graviton is massive or not.\n\nIn
this talk we present new results obtained by studying gravitational pertu
rbations of non-spinning black holes\, when the underlying theory of gravi
ty features gravitons with a non-vanishing mass term. We provide a detaile
d study of the gravitational signals produced when a small particle plunge
s or inspirals into a large black hole. Our results should also describe t
he gravitational collapse to black holes and explosive events such as supe
rnovae. We show how merging objects up to 1Gpc away or collapsing stars in
the nearby galaxy can be used to constrain the mass of the graviton to be
smaller than ∼ 10^(−23) eV\, with low-frequency detectors. We also pr
esent a detailed investigation of new modes\, that suggest how the absence
of dipolar gravitational waves from black hole binaries may be used to ru
le out entirely such theories. These results are particularly relevant for
next generation of space interferometers like LISA\, which has extreme-ma
ss-ratio mergers among its primary targets.\n\nhttps://agenda.infn.it/even
t/15395/contributions/83777/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83777/
END:VEVENT
BEGIN:VEVENT
SUMMARY:GW observation in the Space
DTSTART;VALUE=DATE-TIME:20190220T133500Z
DTEND;VALUE=DATE-TIME:20190220T141000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84039@agenda.infn.it
DESCRIPTION:Speakers: Danzmann Karsten (Max Planck Institute for Gravitat
ional Physics (AEI) - Hannover)\nhttps://agenda.infn.it/event/15395/contri
butions/84039/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84039/
END:VEVENT
BEGIN:VEVENT
SUMMARY:GW observation on the Earth
DTSTART;VALUE=DATE-TIME:20190220T130000Z
DTEND;VALUE=DATE-TIME:20190220T133500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84038@agenda.infn.it
DESCRIPTION:Speakers: Giovanni Losurdo (INFN Pisa)\nhttps://agenda.infn.it
/event/15395/contributions/84038/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84038/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dark sector evolution in Horndeski models
DTSTART;VALUE=DATE-TIME:20190220T112300Z
DTEND;VALUE=DATE-TIME:20190220T114000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83776@agenda.infn.it
DESCRIPTION:Speakers: Francesco Pace (University of Manchester)\nDespite t
he good agreement between theoretical predictions and observational result
s\, the cosmological constant is not a satisfactory explanation for the ac
celerated expansion of the universe. Hence an intense theoretical effort h
as been devoted to the study of models beyond General Relativity plus a co
smological constant.\n\nIn this talk\, I will present ongoing work on the
study of the properties of the dark sector to describe Horndeski models in
terms of a non-trivial fluid within the Equation of State formalism. I wi
ll apply the framework to derive approximate expressions which give a simp
le physical intuition of the problem at hand and to understand theoretical
ly modified gravity parameters and effects on observables. This will be li
nked to results from other perturbative approaches used in the literature.
\n\nhttps://agenda.infn.it/event/15395/contributions/83776/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83776/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Corpuscular gravity: from cosmology to black holes
DTSTART;VALUE=DATE-TIME:20190220T110600Z
DTEND;VALUE=DATE-TIME:20190220T112300Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83807@agenda.infn.it
DESCRIPTION:Speakers: Roberto Casadio (BO)\nCorpuscular gravity has origin
ated from the observation that a black hole can be viewed as a Bose-Einste
in condensate at the critical point\, with a large occupation number of (s
oft off-shell) gravitons and no central singularity. This innovative appro
ach moves away from the semi-classical picture of quantum field theory on
curved backgrounds and considers self-gravitating systems as truly quantum
. We shall introduce the idea that the gravitational state of the whole Un
iverse can be described as a Cosmological Dark Energy Condensate behaving
like a quasi-de Sitter Universe and then discuss the crucial role of regul
ar baryonic matter and the way it interacts with the cosmological condensa
te.\n\nhttps://agenda.infn.it/event/15395/contributions/83807/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83807/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Black holes in an effective field theory extension of general rela
tivity
DTSTART;VALUE=DATE-TIME:20190220T104900Z
DTEND;VALUE=DATE-TIME:20190220T110600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83775@agenda.infn.it
DESCRIPTION:Speakers: Masashi Kimura (Instituto Superior Tecnico\, Univers
idade de Lisboa)\nEffective field theory methods suggest that some rather-
general extensions of General Relativity include higher-order curvature co
rrections\, with small coupling constants. In this talk\, we discuss black
hole solutions in such a framework. First\, we construct spherically symm
etric black hole solutions and study gravitational perturbation around the
m. Despite the higher-order operators of the theory\, we show that lineari
zed field equations obey second-order differential equations. We also stud
y slowly rotating solutions around spherically symmetric black hole soluti
ons and show that the spacetimes do not have $Z_2$ symmetry due to the par
ity violating term.\n\nhttps://agenda.infn.it/event/15395/contributions/83
775/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83775/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ergoregion instability of exotic compact objects
DTSTART;VALUE=DATE-TIME:20190220T103200Z
DTEND;VALUE=DATE-TIME:20190220T104900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83774@agenda.infn.it
DESCRIPTION:Speakers: Elisa Maggio (University of Rome La Sapienza)\nGravi
tational-wave astronomy can give us access to structure of black holes\, p
otentially probing microscopic corrections at the horizon scale. Some quan
tum-gravity models of exotic compact objects replace the event horizon by
a reflective surface. Spinning horizonless compact objects with these prop
erties may be unstable against an ergoregion instability.\nIn this talk we
investigate a model consisting of a Kerr geometry with a reflective surfa
ce near the horizon and we analyse its instability under scalar\, electrom
agnetic and gravitational perturbations. We derive analytically the quasi-
normal mode frequencies and the instability time scale of unstable modes i
n the black-hole limit. We show that the instability for electromagnetic a
nd gravitational perturbations is generically stronger than in the scalar
case and it requires larger absorption at the surface to be quenched. This
result has important consequences for the viability of exotic compact obj
ects as alternatives to black holes.\n\nhttps://agenda.infn.it/event/15395
/contributions/83774/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83774/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Massive Gravity
DTSTART;VALUE=DATE-TIME:20190220T091000Z
DTEND;VALUE=DATE-TIME:20190220T094500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84037@agenda.infn.it
DESCRIPTION:Speakers: Claudia de Rham (Imperial College London)\nhttps://a
genda.infn.it/event/15395/contributions/84037/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84037/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Echoes of modified gravity
DTSTART;VALUE=DATE-TIME:20190220T083500Z
DTEND;VALUE=DATE-TIME:20190220T091000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84036@agenda.infn.it
DESCRIPTION:Speakers: Vitor Cardoso (Instituto Superior Tecnico Lisboa)\nh
ttps://agenda.infn.it/event/15395/contributions/84036/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84036/
END:VEVENT
BEGIN:VEVENT
SUMMARY:String theory
DTSTART;VALUE=DATE-TIME:20190220T080000Z
DTEND;VALUE=DATE-TIME:20190220T083500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84035@agenda.infn.it
DESCRIPTION:Speakers: Marika Taylor (University of Southampton )\nhttps://
agenda.infn.it/event/15395/contributions/84035/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84035/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sagnac gyroscopes and fundamental physics
DTSTART;VALUE=DATE-TIME:20190219T164300Z
DTEND;VALUE=DATE-TIME:20190219T170000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83840@agenda.infn.it
DESCRIPTION:Speakers: Angela Dora Vittoria Di Virgilio (PI)\nSagnac Gyrosc
opes attached to the Earth surface are sensitive to gravito-magnetism\, an
d in principle the confrontation with independent measurements of the Eart
h rotation rate gives the possibility to measure the Lense Thirring effect
without the necessity to map the gravitational field\, independently from
the space measurements. This is feasible or not depending on how ideal is
the Sagnac gyroscopes we have at our disposal. Moreover the same kind of
apparatus built on small scale are in principle ideal for the many kind of
applications necessary to develop inertial platforms. Ring laser gyros a
re at present the most sensitive Sagnac gyros\, the data of the prototype
GINGERINO are used to discuss the feasibility of large scale apparatus and
short size apparatus.\n\nhttps://agenda.infn.it/event/15395/contributions
/83840/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83840/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Systematic errors in high precision gravity measurements by light-
pulse atom interferometry on ground and in space
DTSTART;VALUE=DATE-TIME:20190219T162600Z
DTEND;VALUE=DATE-TIME:20190219T164300Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84024@agenda.infn.it
DESCRIPTION:Speakers: Anna Maria Nobili (Università di Pisa\, Dipartiment
o di Fisica "E. Fermi")\nThe acceleration of free falling atoms as measure
d by light-pulse atom interferometry (AI) equals the exact value experienc
ed by the atoms only if the acceleration is constant. Since the gravitatio
nal field is non-uniform a variable term is always present whose contribut
ion is measured only approximately\, the experimental value being systemat
ically smaller than the theoretical one. The more the acceleration deviate
s from uniformity\, the less good is the approximate value measured by the
instrument. This systematic error limits the absolute measurement of th
e local gravitational acceleration $g$ as well as measurement of the unive
rsal constant of gravity $G$ or attempts to detect gravitational waves by
means of gravity gradiometers based on AI. Testing the Universality of Fr
ee Fall (or the Weak Equivalence Principle) with atom interferometry requi
res a dual AI\, whereby the free fall accelerations of different atoms in
the field of the Earth are measured and subtracted\, searching for tiny no
n-zero differences which would indicate a violation. Unless the two specie
s are manipulated with the same laser\, thus ensuring that the time inter
val between subsequent laser pulses is the same for both species\, the sys
tematic error reported here makes the test utterly impossible on ground\,
and sets severe limitations in orbit. With the same laser the systematic e
rror cancels out\, and less stringent limitations become dominant. Howeve
r\, such a requirement makes the choice of different atom species that ca
n be subjected to testing very limited. In practice\, most tests use $^{
87}\\rm Rb$ and $^{85}\\rm Rb$\, differing by two neutrons only.\n\nhttps:
//agenda.infn.it/event/15395/contributions/84024/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84024/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A new measurement of the Earth’s gravitomagnetic field a century
after the formulation of the Lense-Thirring effect
DTSTART;VALUE=DATE-TIME:20190219T160900Z
DTEND;VALUE=DATE-TIME:20190219T162600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83771@agenda.infn.it
DESCRIPTION:Speakers: David Lucchesi (1. Istituto di Astrofisica e Planeto
logia Spaziali (IAPS/INAF)\, Via Fosso del Cavaliere\, 100\, 00133 Tor Ver
gata\, Roma)\nThe Laser Ranged Satellites Experiment (LARASE) aims to test
the gravitational interaction in the weak-field and slow-motion limit and
compare\, consequently\, the predictions of Einstein’s theory of genera
l relativity (GR) with those of other alternative theories of gravitation.
In particular\, a goal of LARASE is to improve the modelling of the non-g
ravitational perturbations (NGP) on the LAGEOS\, LAGEOS II and LARES satel
lites in such a way to further improve their precise orbit determination i
n order to better extract\, from their orbital residuals\, the expected ti
ny relativistic effects. Indeed\, the motion of these passive laser-ranged
satellites along nearly geodesics of spacetime may be a posteriori recons
tructed through a careful modelling of the main NGP that act on their surf
ace and\, in more general terms\, of their overall dynamical models. We wi
ll focus upon two recent LARASE results: the development of a new model f
or the spin evolution of the satellites and of one to account for the very
subtle effects on their orbits that are produced by the thermal thrust pe
rturbations. Concerning the gravitational perturbations due to the deviati
on of the Earth's mass distribution from that of a perfect sphere\, we wil
l discuss our improvements in the modelling of the Earth's even zonal harm
onics coefficients based on GRACE data\, specifically in their time-depend
ency. Finally\, we will show our new results for a refined measurement of
the Lense-Thirring precession on the combined orbits of the LAGEOS\, LAGEO
S II and LARES satellites. This relativistic precession arises from the gr
avitomagnetic field of the Earth produced by its angular momentum. Gravito
magnetism describes\, in Einstein’s GR\, the curvature of spacetime prod
uced by mass-currents\, with important consequences in the astrophysics of
high-energy phenomena as well as possible cosmological consequences relat
ed to Mach’s Principle.\n\nhttps://agenda.infn.it/event/15395/contributi
ons/83771/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83771/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The LAG experiment
DTSTART;VALUE=DATE-TIME:20190219T155200Z
DTEND;VALUE=DATE-TIME:20190219T160900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83768@agenda.infn.it
DESCRIPTION:Speakers: Luciano Di Fiore (INFN - Napoli)\nIn a laboratory gr
avitational experiment one of the most critical elements is represented by
the source of the gravitational field. For state-of-art measurements\, a
precise characterization of the field and the possibility to modulate the
amplitude are needed. Usually one or more moving masses are used. We desc
ribe a new actuation technique for gravity experiments based on a liquid F
ield Mass. The basic idea is to modulate the gravity force acting on a tes
t mass by controlling the level of a liquid in a suitable container. This
allows us to produce a periodically varying gravity force without moving p
arts (apart the liquid level) close to the Test Mass. Italian INFN (Nation
al Institute of Nuclear Physics) has recently funded a R&D experiment\, na
med LAG (Liquid Actuated Gravity) to test principle of operation and perfo
rmance of the liquid gravity actuator. We will describe in detail the most
relevant aspects of the experiment and discuss how it can be used in grav
ity measurements. In particular we analyse a proposed application for impr
oving test of the inverse square law in the mm to cm region.\n\nhttps://ag
enda.infn.it/event/15395/contributions/83768/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83768/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Archimedes Experiment
DTSTART;VALUE=DATE-TIME:20190219T153500Z
DTEND;VALUE=DATE-TIME:20190219T155200Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83762@agenda.infn.it
DESCRIPTION:Speakers: Paola Puppo (ROMA1)\nArchimedes is an experiment con
ceived to shed light on one of the most intriguing topics of the modern ph
ysics: the interaction between the gravitational field and the vacuum fluc
tuations. The experiment will measure the force exerted by the gravitation
al field on a Casimir cavity\, whose vacuum energy is modulated with a sup
erconductive transition\, by using a balance as a small force detector. Ar
chimedes is an INFN six-year project that will be installed in the SARGRAV
laboratory placed in an old mine located the Sardinia italian region. Thi
s site is characterized by a very low seismic noise so it is the ideal env
ironment for null force experiments and for third-generation gravitational
waves interferometers like ET.\n\nhttps://agenda.infn.it/event/15395/cont
ributions/83762/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83762/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravity on antimatter
DTSTART;VALUE=DATE-TIME:20190219T144000Z
DTEND;VALUE=DATE-TIME:20190219T151500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84029@agenda.infn.it
DESCRIPTION:Speakers: Michael Doser (CERN)\nhttps://agenda.infn.it/event/1
5395/contributions/84029/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84029/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum tests
DTSTART;VALUE=DATE-TIME:20190219T140500Z
DTEND;VALUE=DATE-TIME:20190219T144000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83851@agenda.infn.it
DESCRIPTION:Speakers: Claus Laemmerzahl (University of Bremen)\nQuantum me
chanics is at the basis of our understanding of all matter and - since wit
h the behavior of matter we explore space and time - also of our understan
ding of space-time. In the recent years\, also quantum technologies became
more and more important for practical purposes. This includes quantum sen
sors\, quantum metrology\, quantum information\, quantum cryptography\, qu
antum computing\, etc. Of particular importance is the coupling of quantum
matter to gravity. In this talk we collect the foundations of quantum mec
hanics\, the foundations of relativistic gravity\, and corresponding tests
\, in particular tests exploring the quantum-gravity interaction. Also the
relevance of this research for practical purposes is described.\n\nhttps:
//agenda.infn.it/event/15395/contributions/83851/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83851/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geodesy
DTSTART;VALUE=DATE-TIME:20190219T133000Z
DTEND;VALUE=DATE-TIME:20190219T140500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-84028@agenda.infn.it
DESCRIPTION:Speakers: Juergen Mueller (Leibniz University Hannover)\nhttps
://agenda.infn.it/event/15395/contributions/84028/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/84028/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Testing Theories of Gravity via Shadow of a Magnetised Accretion F
low onto a Black Hole
DTSTART;VALUE=DATE-TIME:20190219T110900Z
DTEND;VALUE=DATE-TIME:20190219T112600Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83764@agenda.infn.it
DESCRIPTION:Speakers: Yosuke Mizuno (ITP\, Goethe University Frankfurt)\nT
he upcoming sub-millimetre VLBI images of Sgr A* by the EHT Collaboration
are expected to provide critical evidence for the existence of this superm
assive black hole. In the near future\, strong field images could be used
to test both deviations from General Relativity as well as different model
s for the compact object at the Galactic Centre. In this work we assess ou
r present and future ability to determine whether such images correspond t
o a Kerr black hole\, a dilaton black hole from an alternative theory of g
ravity or a boson star. We perform GRMHD simulations and use GRRT calculat
ions to generate synthetic images of the magnetised accretion flow onto ea
ch of these objects. We provide synthetic images based on the 2017 EHT and
future VLBI observations and use image metrics to quantify our ability to
distinguish between these objects.\n\nhttps://agenda.infn.it/event/15395/
contributions/83764/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83764/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravitational Waves from Oscillaton Star Collisions
DTSTART;VALUE=DATE-TIME:20190219T105200Z
DTEND;VALUE=DATE-TIME:20190219T110900Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83763@agenda.infn.it
DESCRIPTION:Speakers: Helfer Thomas ()\nI will talk about the GW signature
s from the collisions of Oscillatons -- which are long-lived non-topologic
al solutions of massive scalar fields. I will describe the technical chall
enges and present the GW wave forms of such collisions calculated using th
e numerical relativity code GRCHOMBO. I will show that for black hole end
states\, the total gravitational waves energy released in such collisions
is more than that of BH-BH collisions of equal masses by a significant amo
unt.\n\nhttps://agenda.infn.it/event/15395/contributions/83763/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83763/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Weak field and full GR cosmological simulations
DTSTART;VALUE=DATE-TIME:20190219T103500Z
DTEND;VALUE=DATE-TIME:20190219T105200Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83787@agenda.infn.it
DESCRIPTION:Speakers: Marco Bruni ()\nIn this talk I will describe progres
ses in considering GR effects in the dynamics of structure formation. Firs
t I will present results of a nonlinear post-Friedman approximation\, a ki
nd of post-Newtonian formalism. Then I will focus on recent fully nonlinea
r numerical relativity simulations. Numerical relativity is a fundamental
tool in the modelling of gravitational waves sources\, but its applicatio
n to cosmology is in its infancy. As more interdisciplinary work between t
he gravitational waves and the cosmology communities will develop\, in the
next few years numerical relativity may become a fundamental tool for und
erstanding the extent to which we can trust standard newtonian N-body sim
ulations on the largest scales. First results of simulations representing
the full GR nonlinear evolution of initial perturbations in a Einstein de
Sitter background are: 1) back-reaction effects on the overall expansion
of the model are very small\; 2) voids expansion rate is significantly hi
gher than that of the background\; 3) over-densities can reach turn-around
much earlier than predicted by the standard top-hat model. To establish t
he significance of these results is the goal of future work.\n\nhttps://a
genda.infn.it/event/15395/contributions/83787/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83787/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Numerical Relativity
DTSTART;VALUE=DATE-TIME:20190219T090500Z
DTEND;VALUE=DATE-TIME:20190219T094000Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83938@agenda.infn.it
DESCRIPTION:Speakers: Luciano Rezzolla (Goethe University of Frankfurt)\nh
ttps://agenda.infn.it/event/15395/contributions/83938/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83938/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mathematical Relativity
DTSTART;VALUE=DATE-TIME:20190219T083000Z
DTEND;VALUE=DATE-TIME:20190219T090500Z
DTSTAMP;VALUE=DATE-TIME:20201024T204905Z
UID:indico-contribution-15395-83937@agenda.infn.it
DESCRIPTION:Speakers: Piotr T. Chrusciel (University of Wien)\nhttps://age
nda.infn.it/event/15395/contributions/83937/
LOCATION:"Sapienza" University\, Phys. Dept. Marconi Aula Amaldi
URL:https://agenda.infn.it/event/15395/contributions/83937/
END:VEVENT
END:VCALENDAR