AAS 196th Meeting, June 2000
Session 50. Active Galaxies
Display, Thursday, June 8, 2000, 9:20am-4:00pm, Empire Hall South

## [50.02] The AGN candidate in M82: the remnant of a hypernova?

H. Matsumoto (Massachusetts Institute of Technology), T.G. Tsuru (Kyoto University), S. Matsushita, R. Kawabe (Nobeyama Radio Observatory), A. Prestwich (Center for Astrophysics)

We analyzed the public data of M82 obtained with the High Resolution Camera onboard the Chandra X-ray Observatory. The observations were made on Oct. 28, 1999 and Jan. 20, 2000. We concentrated on the central region of M82 to look for any evidence of the AGN suggested by the ASCA observation (Ptak & Griffiths 1999; Matsumoto & Tsuru 1999). We detected several sources and we found that most of them showed time variability. The radio source 41.30+59.6, which was considered to be a SNR by radio observations, showed rather large time variability: the counting rate changed from 8\times10-2 c/s at the first observation to 5 \times 10-1 c/s at the second observation. If we assume the spectral shape of this source to be the same as that of the AGN candidate detected with ASCA, the luminosity at the second observation is 6 \times 1040 erg/s in the 0.5 -- 10 keV band, which suggests that this source may be the AGN rather than the SNR, though its position was not consistent with the center of M82. Furthermore, a molecular superbubble surrounding this source was found by the radio observation (Matsushita et al. 2000). The kinetic energy of the superbubble is ~1055 erg, which suggests that this source may be the remnant of a hypernova, and that this source may be an medium-massive blackhole. HM is supported by the JSPS Postdoctoral Fellowship for Research Abroad.