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arXiv · 0907.4977

X-ray and Radio Variability of M31*, The Andromeda Galaxy Nuclear Supermassive Black Hole

Michael R. Garcia·Richard Hextall·Frederick K. Baganoff·Jose Galache·Fulvio Melia·Stephen S. Murray·Frank A. Primini·Lorant O. Sjouwerman·Ben Williams
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Abstract

We confirm our earlier tentative detection of M31* in X-rays and measure its light-curve and spectrum. Observations in 2004-2005 find M31* rather quiescent in the X-ray and radio. However, X-ray observations in 2006-2007 and radio observations in 2002 show M31* to be highly variable at times. A separate variable X-ray source is found near P1, the brighter of the two optical nuclei. The apparent angular Bondi radius of M31* is the largest of any black hole, and large enough to be well resolved with Chandra. The diffuse emission within this Bondi radius is found to have an X-ray temperature ~0.3 keV and density 0.1 cm-3, indistinguishable from the hot gas in the surrounding regions of the bulge given the statistics allowed by the current observations. The X-ray source at the location of M31* is consistent with a point source and a power law spectrum with energy slope 0.9+/-0.2. Our identification of this X-ray source with M31* is based solely on positional coincidence.

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Michael R. Garcia, Richard Hextall, Frederick K. Baganoff, Jose Galache, Fulvio Melia, Stephen S. Murray, Frank A. Primini, Lorant O. Sjouwerman, Ben Williams. 2009-07-28. X-ray and Radio Variability of M31*, The Andromeda Galaxy Nuclear Supermassive Black Hole. https://doi.org/10.1088/0004-637x%2F710%2F1%2F755

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