By using ASCA and Chandra, we discovered a new type of black hole, intermediate massive black hole (IMBH), at the off-center position in the starburst galaxy M82. We also found and expanding molecular super bubble (EMSB) surrounding the IMBH with Nobeyama Millimeter Array.
After the discoveries, we made follow-up IR observation of the IMBH with Subaru Telescope in this study and found seven young star clusters in the region. One of the seven star clusters, which we detected with Subaru Telescope observation, was identified with the IMBH within the absolute position accuracy. The results suggest the IMBH was formed in the starburst activity in 10⁶ ~ 10⁷ yrs ago. We also introduced a new formation scenario of SMBH through the merging of IMBHs, which fall into galaxy center by the dynamical friction. We also made X-ray spectral studies for the IMBH in M82 and found that no model describes the spectral nature.
Next step of the research is to measure the angular momentum of a black hole by detecting X-ray polarization and investigate the evolution history of IMBH and SMBH. Thus, we have been developing a new type of X-ray imaging spectrometer, Hybrid X-ray Imaging Spectrometer, and back supportless X-ray CCD with a thick depletion layer used in the camera. By introducing N type wafer of silicon for the CCD, we achieve a thick depletion layer of 130μm, which is about twice thicker than the latest X-ray CCD onboard on X-ray satellite.