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Date and Time of the Query: 2019-06-27 T00:46:57 PDT
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For refcode 1997ApJ...482..133M:
Retrieve 17 NED objects in this reference.
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1997ApJ...482..133M X-Ray Properties of Early-Type Galaxies as Observed with ASCA H. MATSUMOTO, K. KOYAMA, H. AWAKI, AND T. TSURU Department of Physics, Kyoto University, Sakyo-ku, Kyoto, Japan 606-01 M. LOEWENSTEIN Laboratory for High Energy Astrophysics, NASA/Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 AND K. MATSUSHITA Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan 113 Received 1996 September 19; accepted 1997 January 9 ABSTRACT We have systematically investigated the Advanced Satellite for Cosmology and Astrophysics (ASCA) spectra of 12 early-type galaxies. This paper presents the global spectral properties of these systems based on a larger sample than in any previous ASCA study. The X-ray spectra were uniformly fitted by a two-component model consisting of hard X-rays from thermal emission with a temperature of about 10 keV or from a power law with index 1.8, plus soft X-rays from a thin thermal plasma with temperature ranging from 0.3 to 1 keV. The X-ray luminosities of the hard component are found to be proportional to the blue-band luminosities, while those of the soft component show large scatter with no clear correlation. The metal abundances determined from the soft component are systematically lower than solar, with a mean value of about 0.3 solar. We examine the relationships between the temperature and volume emission measure and between the gas temperature and the stellar velocity dispersion. The volume emission measures for early-type galaxies plotted as a function of the gas temperature are well below the extrapolated line found in clusters of galaxies, indicating that early-type galaxies are relatively gas poor compared with galaxy clusters. The ratio of the stellar kinetic energy per unit mass to the thermal energy of the hot gas per unit mass ({beta_spec_) is less than unity. We found no systematic relationship between X-ray properties and environment, suggesting that the interaction between interstellar matter and the intracluster medium is not strong. Subject headings: galaxies: abundances-galaxies: elliptical and lenticular, cD-X-rays: galaxies-X-rays: ISM
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