X-RAY AND RADIO VARIABILITY OF M31*, THE ANDROMEDA GALAXY NUCLEAR SUPERMASSIVE BLACK HOLE

• Main Authors: Garcia, M. R. (Author), Hextall, Richard (Author), Galache, Jose (Author), Melia, Fulvio (Author), Murray, Stephen S. (Author), Primini, F. A. (Author), Sjouwerman, Loránt O. (Author), Williams, Ben (Author), Baganoff, Frederick K (Author)
• Other Authors: MIT Kavli Institute for Astrophysics and Space Research (Contributor), Baganoff, Frederick K. (Contributor)
• Format: Article
• Language: English
• Published: Institute of Physics/American Astronomical Society, 2015-03-19T19:26:08Z.
• Subjects: Article
• Online Access: Get fulltext

 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[superscript -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.