Conveners
Multiwavelength and Multi-Messenger Observations of Active Galactic Nuclei: Block 1
- Narek Sahakyan (ICRANet-Armenia)
Description
This parallel session will focus on the multiwavelength and multi-messenger observations of jetted active galactic nuclei (AGN), which are the most powerful persistent sources of radiation in the Universe. Blazars, the most extreme subclass of AGN having jets that move relativistically towards the observer, are characterized by highly variable non-thermal emission across the entire electromagnetic spectrum, from radio up to very high energy gamma-ray bands. The multiwavelength observations of blazars and theoretical interpretations of the results allows to study the physics of relativistic outflows under extreme conditions as well as to probe the physical condition of the plasma in the jet. The recent association of a very high-energy neutrino, IceCube-170922A, with a flaring blazar, TXS 0506+056, opened a new era for jet research providing unprecedented opportunity to combine information from different messengers to investigate long-standing problems in jet physics. The recent progress in multiwavelength and multi-messenger observations of blazars will be presented and discussed.
Jets from super-massive-black-holes radiate photons over the whole electromagnetic spectrum, from the radio band up to TeV gamma-rays. Understanding the radiative mechanisms at work is a fundamental step for the study of particle acceleration in black-hole's jets, and to constrain jets structure, composition, and propagation. Using the information from multi-wavelength observations, several...
The observation of a very-high-energy neutrino by IceCube (IceCube-170922A) and its association with the flaring blazar TXS 0506+056 provided the first multimessenger observations of a blazar jet, demonstrating the important role of protons in their dynamics and emission. In this paper, we present SOPRANO, a new conservative implicit kinetic code which follows the time evolution of the...
Blazars are a subclass of active galaxies with jets closely aligned to the observer's line of sight. In addition, they are the most powerful persistent sources across the electromagnetic spectrum in the universe. The detection of a high-energy neutrino from the flaring blazar TXS 0506+056 and the subsequent discovery of a neutrino excess from the same direction have naturally strengthened the...
The progenitors of high-energy (HE) neutrinos detected by the IceCube observatory (> 30 TeV) remain on the discussion. Astrophysical events such as Gamma-ray bursts (GRBs), Supernova remnants (SNR), Tidal disruption events, and Active galactic nuclei (AGN) are proposed as HE neutrinos progenitors. So far, the only detection in space-time coincidence with a neutrino event is by the TXS...
We utilize radio interferometric (VLBI) observations to tackle the problem of determining high-energy neutrino origins. Specifically, we find blazars positionally associated with IceCube neutrino detections to exhibit stronger parsec-scale radio emission compared to the rest of the sample. The probability of a chance coincidence is only 4*10^-5 (4.1 sigma). There are at least 70 bright blazars...
The Fermi blazar observations show a strong correlation between $\gamma$-ray luminosities and spectral indices. BL Lac objects are less luminous with harder spectra than flat-spectrum radio quasars (FSRQs). Interestingly FSRQs are evident to exhibit a Keplerian disc component along with a powerful jet. We compute the intrinsic jet luminosities by beaming corrections determined by different...
The BL Lacs Mrk 421 and Mrk 501 show fast variability in the TeV-band flares, indicating a compact emission region. The lack of correlation between X-ray and TeV flux hints at more than one emission zone. Both sources have shown temporary extreme behavior. In this work, we used a lepto-hadronic model with two-zone emission to explain the spectral energy distribution during the very...
High-redshift blazars are among the most powerful objects in the Universe. The spectral and temporal properties of 33 distant blazars (z > 2.5) detected in the high-energy gamma-ray band will be discussed using the Fermi-LAT and Swift Ultraviolet and Optical Telescope/X-ray Telescope (UVOT/XRT) data accumulated during 2008-2018. The properties of those blazar jets obtained by modeling the...
