The detection of orbital eccentricity in gravitational waves (GWs) will provide us with unique and valuable information about the astrophysical origin and evolution of compact binary systems. In recent years, the expectations for observing eccentricity signatures in GWs have increased due to the continuous improvement of GW detectors and data-analysis techniques. For this purpose, eccentric...
The Extreme Mass Ratio Inspirals (EMRIs) are critical astrophysical systems in the study of gravitational waves, where a stellar-mass compact object spirals into a supermassive black hole. Accurate modeling of EMRIs is essential for the success of space-based gravitational wave detectors like LISA. This work presents an improved Effective-One-Body (EOB) model tailored for simulating the EMRIs...
Describing the dynamics of eccentric black hole binaries remains an open problem in General Relativity. Oscualting equations based on energy and angular momentum balance have been found inconsistent with predictions obtained via orbit averaging, particularly in the parabolic regime. This inconsistency arises from the gauge-dependent definitions of energy and angular momentum. We reparametrize...
Tidal Love numbers provide us a handle to test the nature of compact objects, as well as theories of gravity. There have been several clarifications recently, which makes our understanding of these Love numbers better. But further investigations have led to more confusion. I plan to discuss these recent developments and the confusing nature of recent literature on these issues. I will show...
The effective one-body (EOB) approach is a proven technique for generating fast and accurate models for the motion and radiation of coalescing compact binaries. At its core, it consists of a specific resummation strategy that takes as input the results of the perturbative schemes used to tackle the two-body problem, notably the post-Newtonian (PN) expansion, the post-Minkowskian (PM)...
Gravitational radiation reaction for compact binary systems has historically been studied using post-Newtonian theory, which is well adapted for the inspiraling phase and has the advantage of yielding fully analytical results. I will present recent work where we obtain the equations of motion for the two-body problem at 4.5PN order, in a generic frame. We prove for the first time the validity...
We present results on the linear response of four dimensional magnetic black holes and regular topological stars arising from dimensional compactification of Einstein-Maxwell theory in five dimensions.
We discuss the stability of these solutions under both radial and nonradial perturbations, both in the frequency and in the time domain.
Assuming spherical symmetry we consider primordial black hole formation from the collapse of adiabatic cosmological perturbations of a massless scalar field, sourced by a time independent curvature profile $\mathcal{R}(r)$ imposed on super horizon scale. We have proved that a massless scalar field is equivalent to a perfect fluid where the pressure is equal to the total energy density (i.e....
Regarding proposals for modified gravity theories, there is a popular class commonly denominated as scalar-tensor theories, where new scalar fields are introduced that do not interact with gravity in the standard fashion. There is a subclass of such theories that present Screening mechanisms, which allow them to modify gravitational phenomena at large scales while preserving General...
Black hole quasi-normal mode (QNM) frequency spectrums can probe deviations from General Relativity. We construct an effective field theory scheme for QNMs in shift-symmetric scalar-tensor theories with second order equations, exploiting the behaviour of the black holeโs scalar charge in the large mass limit. We find a drastic simplification; the QNM calculation reduces to solving sourced QNMs...
Phase transitions can play an important role in the cosmological constant problem, allowing the underlying vacuum energy, and therefore the value of the cosmological constant, to change. Deep within the core of neutron stars, the local pressure may be sufficiently high to trigger the QCD phase transition, thus generating a shift in the value of the cosmological constant. The gravitational...
Many works have explored the emergence and properties of compact object solutions including black holes, in models with a metric tensor and a scalar field within the Horndeski framework. Studying the quasinormal mode (QNM) spectrum of hairy black holes is particularly useful when considering the potential of observing hairy solutions in nature. In this talk we discuss how the QNMs of such...
The mass of a black hole can dynamically evolve due to various physical processes, such as for instance accretion, Hawking radiation, absorption
of gravitational/electromagnetic waves, superradiance, etc. This evolution might have an impact on astrophysical observables like the ringdown gravitational signal. An effective description of a spherically symmetric black hole with evolving mass...
Eccentricity is one of the key parameters to describe a binary system, however, defining it in General Relativity is a highly nontrivial problem. Nevertheless, achieving a consistent definition of orbital eccentricity is a pressing issue for both current and future gravitational wave observations. We present a new approach to consistently define the binary eccentricity in General Relativity...
The multi-messenger (MM) observations of binary neutron star (BNS) mergers provide a novel approach to trace the distance-redshift relation, crucial for understanding the expansion history of the Universe and, consequently, testing the presence of Dark Energy (DE). While the gravitational wave (GW) signal offers a direct measure of the distance to the source, the combined efforts of wide-field...
Extreme mass ratio inspirals (EMRIs), binary systems composed of a stellar mass compact object (SCO) inspiralling to a supermassive black hole (SMBH), are one of the target sources for the Laser Interferometer Space Antenna (LISA). Since EMRIs may spend about $10^{5}$ cycles in the sensitivity band of the interferometer, they are regarded as golden sources to probe new fundamental fields....
The LISA satellite, recently adopted by ESA, is ready to open a new gravitational wave window, targeting sources dim to ground based detectors like LIGO and Virgo.
Extreme mass-ratio inspirals (EMRIs), composed by a massive black hole and a stellar mass secondary, are a among the most peculiar of such new family of binaries. The inspiral phase of these systems falls within the mHz regime of...
Nonlinear effects in black hole perturbation theory may be important for describing a black hole ringdown, as suggested by recent works. I will describe a new class of "quadratic" quasi-normal modes at second order in perturbation theory. Remarkably, not only their frequency but also their amplitude is completely determined by the linear modes themselves. I will present how one can compute...
Recently, studies on numerical evolutions of eccentric binary inspirals found a several orders of magnitude enhancement of the post-ringdown tail amplitude. This characteristic might render the tail a phenomenon of observational interest, opening the way to experimental verification of this general relativistic prediction in the near future. I will present an analytical perturbative model that...
The first detection of a neutron star binary merger has made sharp reality the long-standing paradigm that these cosmic fireworks are exciting laboratories for extreme physics. To get the most out of observations, however, we need accurate modelling of the merger dynamics via numerical relativity simulations. In this respect, the large amount of numerical work carried out over the last decade...
Astrophysical observations of neutron stars allow us to study the physics of matter at extreme conditions which are beyond the scope of any terrestrial experiments. In this work, we perform a Bayesian analysis putting together the available knowledge from the nuclear physics experiments, observations of different X-ray sources, and gravitational wave events to constrain the equation of state...
The multimessenger event GRB 170817A confirmed that short gamma-ray burst jets can be launched from the remnants of a binary neutron star merger environment. The electromagnetic properties of such jets are expected to strongly affect their structure and propagation. In particular, the impact of a finite conductivity may play a key role in the early stages of propagation, i.e. when the jet...
The gravitational collapse of a massive star with a fast-rotating core sets the stage for the onset of magnetorotational core-collapse supernovae (CCSN). The accreting central compact object (either a black hole or a proto-magnetar) is believed to be the central engine that can power up outstanding stellar explosions such as hypernovae and long gamma-ray bursts (GRBs). Current...
The inference of source parameters from gravitational-wave signals relies on theoretical models that describe the emitted waveform. Different model assumptions on which the computation of these models is based could lead to biases in the analysis of gravitational-wave data. In this work, we sample directly on four state-of-the-art binary black hole waveform models from different families, in...
In dense star clusters stars may be disrupted in close encounters with stellar mass black holes. These transients are addressed as โmicro-Tidal Disruption Eventsโ (TDEs). To date, micro-TDEs have not yet been observed but they are promising multi-messenger sources predicted to be detected by next gravitational waves (GW) observatories (i.e. DECIGO) and future all-sky surveys (i.e. LSST,...
I introduce $floZ$, an improved method based on normalizing flows, for estimating the Bayesian evidence (and its numerical uncertainty) from a set of samples drawn from the unnormalized posterior distribution. I validate it on distributions whose evidence is known analytically, up to 15 parameter space dimensions and I demonstrate its accuracy for up to 200 dimensions with $10^5$ posterior...
The tidal Love numbers of self-gravitating compact objects describe their response to external tidal perturbations, such as those from a companion in a binary system, offering valuable insights into their internal structure. For static tidal fields, asymptotically flat black holes in vacuum exhibit vanishing Love numbers in general relativity, even though this property is sensitive to the...
The properties of binaries hosting a Wolf-Rayet star and a compact object
(black hole or neutron star) suggest that such systems could be the progen-
itors of binary compact objects merging via gravitational wave emission. It
is difficult to distinctively determine the road leading to these mergers: many
stellar and binary physical models are still poorly constrained and...
Efficient gravitational waveform models enable us to analyze gravitational wave signals and extract information about the source properties of the compact binary involved in the merger. In this talk, we discuss the improvements made to the NRTidal model, a state-of-the-art model used to describe the tidal interactions between the components of binary neutron stars. The updates include a new...
Dense astrophysical environments, such as globular clusters, could host populations of black holes undergoing scatterings and dynamical captures. The gravitational wave event GW190521 may have originated from such a system, underscoring the need for accurate descriptions to fully leverage the scientific potential of current and future gravitational wave detectors.
We briefly introduce the...
In this talk I will highlight recent developments in computing classical gravity observables within the post-Minkowskian scheme using QFT techniques, the double copy and modern tools of scattering amplitudes.
Gravitational waves (GW) from chirping binary black holes (BBHs) provide unique opportunities to test general relativity (GR) in the strong-field regime. However, testing GR can be challenging when incomplete physical modeling of the expected signal gives rise to systematic biases. In this talk, we discuss the potential influence of wave effects in gravitational lensing (also known as...
We have attempted to mitigate the challenge of connecting the neutron star (NS) properties with the nuclear matter parameters that describe equations of state (EOSs). The efforts to correlate various neutron star properties with individual nuclear matter parameters have been inconclusive.
A Principal Component Analysis is employed as a tool to uncover the connection between multiple nuclear...
