Blazar

Blazars are the most extreme and luminous class of active galactic nuclei (AGN), characterized by relativistic jets of plasma shooting directly toward Earth at speeds exceeding 99% the speed of light. These cosmic lighthouses result from supermassive black holes (typically 100 million to 10 billion solar masses) actively feeding on surrounding matter, creating twin jets perpendicular to their accretion disks. When one jet aims directly at us, relativistic beaming amplifies the observed brightness by factors of 10-100, making blazars visible across billions of light-years.</p><p>First identified in the 1960s as mysterious radio sources, blazars exhibit dramatic variability—brightening or dimming by factors of 10 within hours or days. Notable examples include 3C 273, the first quasar discovered and visible through amateur telescopes despite being 2.4 billion light-years away, and Markarian 501, which produces gamma rays with energies exceeding 10 trillion electron volts.</p><p>Blazars serve as natural laboratories for studying extreme physics, including relativistic plasma behavior and spacetime curvature near black holes. Their rapid variability helps astronomers probe the jet's internal structure, while their high-energy emissions provide insights into cosmic ray acceleration. Modern surveys detect thousands of blazars, with the most distant examples offering glimpses of the universe when it was less than 10% its current age.