Smithsonian Astrophysical Observatory
Weekly Science Updates | 2014 Sep 05
A blazar is a galaxy whose central, supermassive black hole shines intensely as it accretes material from the surrounding region. Although black hole accretion happens in many galaxies and situations, in blazars the infalling material erupts into a powerful, narrow beam of high velocity charged particles that are fortuitously pointed in our direction. These particles produce gamma rays, each photon over a hundred million times more energetic than the highest energy X-ray photons seen by the Chandra X-ray Observatory. Blazars are also generally characterized by having rapid, strong, and incessant variability, among a host of effects resulting from its beam of rapidly moving electrons.
Astronomers suspect that clues to the inner workings of black holes and accretion disks can be discerned from modeling the details of the variability, but this has been a difficult task. The complexity of the variability indicates that the emitting structures are also complex, and constraining the locations and sizes of the emitting sites has been hampered by a lack of long-term, sensitive observations capable of steady monitoring of the changing activity. ...
Stochastic Modeling of the Fermi/LAT γ-ray Blazar Variability - Malgorzata A. Sobolewska et al