Blazars

Blazars are extremely energetic and compact active galactic nuclei (AGN) with relativistic jets pointing toward an observer. Blazars are a subtype of quasars whose jets point toward Earth.

Blazars are so rare that, out of the 1 million quasars identified so far, only 2,700 are blazars.

Formation

When a supermassive black hole at the centre of a galaxy begins accreting material from its surroundings, it forms a very hot accretion disk. Strong magnetic fields develop around the black hole due to the superhot accretion disk. These magnetic fields generate jets of very high-speed particles. These particles travel at nearly the speed of light, causing them to emit high-energy radiation, such as gamma rays and X-rays. When these jets point toward Earth then the AGN is said to be a blazar.

Properties

Blazars have the same properties as a quasar but vary in some aspects like emission spectrum, polarisation, brightness, etc.

Blazars have very high energy outputs that can rival the luminosity of billions of stars on its own. Their energy output can reach up to \(10^{48}\) ergs. They also exhibit extreme variability in terms of brightness often changing on timescales from minutes to years. Just like stars blazars also release flares which have an extreme amount of radiation and energy. In 2006 a blazar named PKS 2155-304 released a blazar flare that had a level of luminosity equivalent to the total energy output by 10,000 Milky Way galaxies combined

Blazars have high polarisation levels of up to 30-50%. Their relativistic jets that are pointing towards Earth can cause extreme brightness and significant relativistic effects.