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How Can a Black Hole Have an Outflow?

-- | July 29, 2014

Question: Black holes are defined as a zone where the gravity is so dense that nothing, not even light, can escape from being drawn in, yet “Fermi Bubbles” are where ” energy often escapes from these systems (Galaxies ) in a jet”. This sounds like a contradiction. Is there an explanation? — Stephen

Answer: The Fermi bubbles are two large gamma-ray structures in located above and below the Galactic center. At the moment there are several theories as to the origin of these bubbles, including past dynamical processes that resulted in large amounts of gas being pushed into these regions. The most plausible dynamical process would be the outflow from a supermassive black hole. Even though black holes swallow matter as it orbits in a disk-like structure around the black hole, a small fraction of that matter escapes vertically via an outflow of material, a consequence of the need for the black hole plus disk system to conserve angular momentum. So, in fact, a black hole system can produce both an inward and outward flow of matter.

Jeff Mangum

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