Conveners
Modeling
- Andrew Taylor
Modeling
- Andrew Taylor
Modeling
- Fabrizio Tavecchio
Dr
Martin Lemoine
(Institut d'Astrophysique de Paris)
23/01/2019, 14:00
Main track
Talk
The acceleration of charged particles to high energies in powerful astrophysical sources such as blazars represents a central question in modern multi-messenger astrophysics. Accelerated particles can interact with and radiate in ambient fields to produce secondary photon or neutrino fluxes, or escape from the source to become part of the cosmic ray spectrum. This presentation will discuss...
Dr
Andreas Zech
(LUTH, Observatoire de Paris)
23/01/2019, 14:40
Main track
Talk
The emerging class of extreme blazars, characterised by very hard high-energy
spectra peaking around TeV energies, pose a challenge for the usual blazar emission
models. While the multi-wavelength emission from high-frequency BL Lac type
blazars can in generally be well interpreted with the single-zone SSC model, the
very hard spectra of extreme blazars (or “ultra-high frequency peaked...
Mr
Matteo Lucchini
(Anton Pannekoek Institute for Astronomy)
23/01/2019, 15:20
Main track
Talk
The jets launched by accreting super-massive black holes can be
some of the brightest sources in the high-energy sky; despite be-
ing discovered decades ago, their physics and energetics are still
poorly understood. The past decade has seen a dramatic improve-
ment in the quality of available data, particularly in the X-ray and
γ-ray bands. However, the semi-analytical modelling of jets...
Dr
Olivier Hervet
(UC Santa Cruz)
23/01/2019, 15:40
Main track
Talk
Most of the TeV high-frequency-peaked BL Lacs (HBLs) show stationary or slow motions of their VLBI radio-knots, in stark contrast with their fast variability.
This problem, known as "the bulk Lorentz factor crisis," indicates that the VLBI motions of these sources are not showing the real flow propagation of the jets. I will present evidence that these stationary radio knots are recollimation...
Ms
Stella Boula
(National and Kapodistrian University of Athens)
23/01/2019, 16:30
Main track
Talk
The launch of Fermi produced a significant number of AGN detections to allow statistical treatment of their properties. It confirmed the Blazar Sequence" established by EGRET and indicated a potentially novel one, namely that of theBlazar Divide" in FSRQs and BL Lacs according to their gamma-ray spectral index and luminosity. An MHD accretion wind model that describes the distribution of...
Dr
Krzysztof Nalewajko
(Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences)
23/01/2019, 16:50
Main track
Talk
Compton dominance, the observed ratio between the high-energy (assumed to be due to inverse Compton) and synchrotron components of the spectral energy distributions of blazars, is an indirect probe of magnetization of their relativistic jets. For most blazars, the Compton dominance is observed in the range 0.3-10, and in the framework of one-zone leptonic models it can be explained by mildly...
Dr
Laura Di Gesu
(Italian Space Agency (ASI))
23/01/2019, 17:10
Main track
Talk
With the advent of the IXPE (Imaging X-ray Polarimetry Explorer) satellite
expected for launch in 2021, the study of the
X-ray polarization properties of several bright nearby sources
will become possible. Blazars are obvious candidates for X-ray
polarization observations.
For instance, a high degree of X-ray polarization is expected from
high-peaked blazars (HBL) because...
Dr
Andrea Tramacere
(Astronomy Department of the University of Geneva,)
24/01/2019, 09:00
Main track
Talk
I will review some of the main phenomenological signatures of the stochastic acceleration acting
in the relativistic jets of blazars. I will link predictions from Monte Carlo simulations
and from the numerical solution of the diffusion equation in momentum space, to the
spectral features observed in the multi-wavelength SED of blazars. In particular, I will focus
on the spectral...
Prof.
Markus Boettcher
(North-West University)
24/01/2019, 09:20
Main track
Talk
Diffusive shock acceleration (DSA) at mildly relativistic shocks
has been argued to be an efficient mechanism for the acceleration
of ultrarelativistic particles blazar jets. Here we present results
of coupled time-dependent simulations of diffusive shock acceleration
and production of synchrotron and Compton emission to model the expected
spectral variability signatures of shocks in...
Dr
Ian Christie
(Northwestern University)
24/01/2019, 09:40
Main track
Talk
Relativistic magnetic reconnection is a strong candidate for the acceleration of particles to high-energies and is a proposed mechanism for the multi-wavelength spectral and temporal variability observed in blazar jets. By coupling recent two-dimensional particle-in-cell simulations of relativistic reconnection with a time-dependent radiative transfer model, we compute the non-thermal emission...
Ms
Ioulia Florou
(National & Kapodistrian University of Athens)
24/01/2019, 10:00
Main track
Talk
Hadronic models of high-energy AGN emission become more relevant than ever before after the latest IceCube results that associate a gamma-ray flaring AGN with high-energy neutrinos. Despite offering a unique framework for the production of high-energy neutrinos, hadronic scenarios have been criticized in the past for being radiatively inefficient. However, an overlooked property of hadronic...
