HEAPOW: A Black Hole Ablaze (2018 Apr 09)
Active galaxies have voracious, central supermassive black holes with masses equivalent to millions or billions of Suns crammed into a space the size of our solar system. These supermassive black holes are feasting from a cosmic smorgasbord of galactic matter (clouds of gas and dust, and perhaps stars and other objects). As this material falls towards the black hole's event horizon (never to be seen again), it emits an enormous quantity of energetic radiation extending all the way up the to the Gamma-ray band, sometimes producing a narrow jet of particles shooting from the black hole for millions of light years into intergalactic space as well. Blazars are particularly extreme types of active galaxies, highly luminous, highly energetic and highly variable. Astronomers believe that the extreme behavior of blazars is a simple consequence of the orientation of the jet from the central black hole, which, for these galaxies, just happens to be pointing at earth. This gives us a good view down the barrel of the jet and the unstable, powerful emission that it produces. The image above is a Gamma-ray image of a large portion of the sky in June, 2015, obtained by the Large Area Telescope on the Fermi Gamma-ray Space Telescope. This image shows a bright Gamma-ray flare from a well-known blazar called 3C 279. As LAT discovered, during a few days last June, 3C 279 became as bright as the brightest Gamma-ray source, the Vela Pulsar, despite the fact that 3C 279 is millions of times more distant than the pulsar. The short Gamma-ray flare from 3C 279 suggests that a powerful disturbance occurred in a very small region near the supermassive black hole. Astronomers are still not sure what caused this outburst, or when or if it will happen again.
Fermi: Record Flare from a Black Hole in a Distant Galaxy
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