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[1.08] Discovery of a Luminous, Variable, Off-Center Source in the Nucleus of M82 with the Chandra High-Resolution Camera

H. Matsumoto, C.R. Canizares (MIT), T.G. Tsuru, K. Koyama (Kyoto Univ.), H. Awaki (Ehime Univ.), S. Matsushita, A. Prestwitch, A.L. Zezas (CfA), N. Kawai (RIKEN), M. Ward (Univ. of Leicester), R. Kawabe (Nobeyama Radio Observatory)

We present results from the observations of the most famous starburst galaxy M82 with the High-Resolution Camera onboard the Chandra X-Ray Observatory. We found nine sources in the central 1'\times1' region, and found no source at the dynamical center. Four of the nine sources showed significant time variability. One of the variable sources, identified with a radio source 41.30+59.6 or 41.5+59.7, showed extremely high luminosity and large time variability (L_{\rm X} = (1 - 9)\times10⁴⁰ erg s^-1). We conclude that this source is the origin of the hard X-ray time variability of M82 detected with ASCA. Furthermore, taking account of its position (9'' away from the dynamical center), this source is a candidate for a medium-massive (10³ - 10⁶ M_\odot) black hole (MMBH). We found that a molecular super bubble with an age of 10⁶ yrs and the kinematic energy of 10⁵⁵ ergs surrounds the source by radio observations. This suggests that explosive starburst activity produced the MMBH and the super bubble.

HM and SM is supported by the JSPS Postdoctoral Fellowships for Research Abroad.