What is a Blazar?
Blazars are among the most luminous phenomena in the universe besides the Big Bang. They are a subtype of active galactic nuclei (AGN), which are created when large clouds of dust and gas generate tremendous friction as they are sucked into a supermassive black hole. This accretion of matter forms a ringlike structure called an accretion disc. Perpendicular to the plane of the disc, powerful relativistic (near light speed) plasma jets are released, which can be observed from Earth using optical/radio telescopes if the jet happens to be pointing towards us. If not, the blazar may be unobservable from our perspective. As a group, objects with the above properties are called active galaxies. The light released by the relativistic jets is so powerful that it can be observed from billions of light years away. Blazars are a subclass of active galaxies, including two types of objects — OVV (optically violent variable) quasars and BL Lacertae objects. Both are characterized by polarized light
The first thing that might cross your mind is, so what exactly is a blazar anyway? A blazar is specific kind of Active Galactic Nuclei (AGN). An AGN is a galaxy with a black hole at the center that is accreting matter. A blazar is an AGN that we happen to be looking at down the jet axis. Blazars are compact, highly variable sources. A subclass of blazars are objects known as BL Lacs, or BL Lacertae objects. These are blazars with intrisincally weak radio emission. All of our chosen sources fall into the category of being BL Lacs. BL Lacs have a characteristic two hump spectral energy distribution (SED). High frequency peaked BL Lacs (HBLs) have a higher frequency peaked synchrotron hump, and likewise with low frequency peaked BL Lacs (LBLs). All of our sources are HBLs. The SED of one of our sources, Markarian 421 shows this two hump distribution. Another interesting question might be, why are HBLs neutrino point source candidates? As can be seen from the SED of Markarian 421 there are
