2009/07/28 by Michael R. Garcia, Richard Hextall, Frederick K. Baganoff +8
Physics and Astronomy · #Andromeda Galaxy #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Black hole (networking) #Bulge #Galaxies: Formation, Evolution, Phenomena #Galaxy #Light curve #Point source #RADIUS #Supermassive black hole #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/710/1/755
25 pages, 8 figures, submitted to ApJ
arxiv created 2009/07/28 · openalex publication_date 2010/01/21 · arxiv updated 2015/05/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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 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.