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Adam Harvey - "The seed factor: how a combination of four observables can unveil the location of the blazar GeV emission" - abstract
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Amar Hekalo - "The Doppler Factor Crisis of TeV blazars" - abstract
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We present here a method for constraining the emission location of γ-rays in powerful, lined blazars (i.e., flat spectrum radio quasars (FSRQs)). We have developed a diagnostic criteria, which we term the seed factor, to differentiate between γ-ray emission due to external Compton (EC) scattering in the broad line region (BLR) and the molecular torus (MT). The seed factor is determined entirely by four observable quantities; the synchrotron and inverse Compton (IC) peak frequencies, and the respective peak luminosities. It may thus be possible to use the seed factor to constrain the emission location in a model-independent way. We also present preliminary results of our analysis regarding the seed factor in quasi-simultaneous multi-wavelength SEDs from the Fermi LAT Bright AGN Sample (LBAS), historical data from the ASDC SED Builder of FSRQs in the the Monitoring Of Jets in Active galactic nuclei with VLBA Experiments (MOJAVE) sample, and quasi-simultaneous multi-wavelength SEDs from the Dynamic SEDs of southern blazars (DSSB) sample. |
Amar Hekalo - "The Doppler Factor Crisis of TeV blazars" - abstract
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Active Galactic Nuclei (AGN) are strong emitters at all wavelengths, often featuring relativisti- cally propagating streams of matter or “jets” from the vicinity of a supermassive black hole at the nucleus of the galaxy. Blazars are a sub-class of AGN, where a jet is pointing almost directly at the observer, leading to relativistic effects such as Doppler beaming and to the illusion of appar- ent superluminal motion. In the most extreme case of so-called TeV blazars, the emission reaches up to the highest observable gamma-ray energies. Studies of the TeV emission imply strong Doppler beaming of highly relativistic jets with Lorentz factors up to 50. Using Very Long Baseline Interferometry (VLBI) in the radio range, the jet speeds can be directly measured. Such studies typically find slow and only slightly relativistic jets, which is in stark contrast to the gamma rays. This discrepancy is known as the Doppler Crisis of TeV blazars. We study a new sample of TeV blazars on the Southern Hemisphere, which are monitored with VLBI as part of the TANAMI program. While most of the TANAMI TeV blazars show slow or stationary jets, some sources do show apparent superluminal motion in line with the expectation of high Lorentz factors in TeV blazars. |
Andrea Gokus - "The Spectral Energy Distribution of the Candidate Neutrino Source TXS0506+056" - abstract
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