Max Planck Institute for Extraterrestrial Physics
Election Year: 1998
Primary Section: 12, Astronomy
Membership Type: Foreign Associate
I have been studying various astronomical objects by means of X-ray spectroscopic observations. During the past twenty years, I have been engaged in several Japanese X-ray astronomy missions. I was responsible for the ASCA satellite, the first X-ray observatory for imaging and high-resolution spectroscopy, which included a significant U.S. contribution. My prime interest is black holes in X-ray binaries and active galactic nuclei. My colleagues and I studied spectroscopic signatures of X-ray binaries containing a black hole, with which I concluded the presence of several hundred, or possibly many more, black holes in our Galaxy. We also found evidence for supermassive black holes in active galactic nuclei from X-ray line spectroscopy. I am also studying X-ray spectra of supernova remnants, galaxies, and clusters of galaxies, with interests in the production of heavy elements and cosmological evolution of element abundances.