Supermassive black holes suck in surrounding materials

Supermassive black holes suck in surrounding materials

Supermassive black holes suck in surrounding materials

Assistant Professor David Ballantyne and his co-authors, J.R. McDuffie (Center for Relativistic Astrophysics) and J.S. Rusin (South Cobb High School student) published an article entitled:  “A Correlation Between the Ionization State of the Inner Accretion Disk and the Eddington Ratio of Active Galactic Nuclei” in The Astrophysical Journal.  The paper addressed supermassive black holes in the centers of galaxies grow by ‘accretion’ -- that is, they suck in material from their surroundings which swirls into the black hole like water going down the drain. Now, the actual physics involved in how an accretion disk works is complicated, and, because these accreting black holes are so very far away, it is very difficult to test accretion disk theories by observations with telescopes. However, these accretion disks get so hot as they swirl around the black hole that they produce X-rays and these X-rays interact with the accreting gas leaving ‘fingerprints’ of accretion physics in the X-ray radiation that astronomers can detect. This paper uses these fingerprints from a number of different accreting black holes and describes the discovery of a relationship between the ionization state of the accreting gas close to a black hole and how rapidly the black hole is being fed. Basically, we see that the more rapidly a black hole is gobbling material, the more highly ionized its accretion disk. The exact implication of this relationship is unclear, but further study will allow new tests of our theories of how black holes grow in the universe.

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