Sloan Digital Sky Survey image of blazar Markarian 421. Source: https://en.wikipedia.org/wiki/Markarian_421#/media/File:SDSS_Mrk_421.jpg
Short Definition:
A blazar is a type of active galaxy nucleus with a jet composed of ionized matter traveling at nearly the speed of light, which direction is nearly towards an observer. Due to the jet almost directly shooting towards Earth, a blazar appears much brighter on observations than in case of facing another direction. Blazars are a source of powerful radiation in all electromagnetic spectrum, especially in high-energy gamma rays. Blazars are among the most energetic phenomena in the universe and are an important subject to research.
Detailed Definition:
Blazars are an extremely bright, starlike object characterized by rapid changes in luminosity and a flat spectrum caused by a jet composed of ionized matter traveling at nearly the speed of light directed at the observer. Blazars emit electromagnetic radiation over a very wide range of frequencies, but mostly distinguished by amount of radio and gamma rays. Due to blazar's instabilities its properties change over time, specifically the variability and intensity of their observable brightness, which is distinguishing blazars from another class of active galactic nucleus, quasars. Blazars are important topics of research in astronomy and astrophysics. Blazar research includes investigation of the properties of accretion disks and jets, the central supermassive black holes and surrounding host galaxies, and the emission of high-energy photons, cosmic rays, and neutrinos.
Etymology:
Coined by 1978 by astronomer Edward Spiegel from BL Lac object and quasar.
Sample Sentence(s):
"Blazars are thought to be active galactic nuclei, with relativistic jets oriented close to the line of sight with the observer." “Strong γ-ray emission is detected in blazars only.”
