NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-26 T12:02:07 PDT
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For refcode 2000PASJ...52..685M:
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Copyright by Astronomical Society of Japan. 2000PASJ...52..685M Metal Abundances in the Hot Interstellar Medium in Early-Type Galaxies Observed with ASCA Kyoko MATSUSHITA Max-Planck-Institut fur extraterrestrische Physik, Postfach 1603, D-85740, Garching, Germany E-mail: matusita@xray.mpe.mpg.de Takaya OHASHI Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Ohsawa Hachioji, Tokyo 192-0397 and Kazuo MAKISHIMA Department of Physics and Research Center for the Early Universe (RESCEU), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Received 1999 December 14; accepted 2000 March 8) Abstract We have analyzed ASCA data of 27 early-type galaxies, and studied the properties of their X-ray emitting ISM (InterStellar Medium) in detail. We found that overlapping lines and free-bound continuum cause strong coupling in the derived abundances of various elements. The abundance determination is also difficult due to the uncertainties in the Fe-L atomic physics, because the Fe-L lines couple with the O and Ne K-lines. However, when the abundances of {alpha}-elements are fixed, all of the plasma codes give similar Fe abundances with a scattering of only 20-30%. To relax the strong coupling among the elements, we included 20% systematic errors in the Fe-L region of the spectra. Then, in X-ray luminous galaxies, the derived abundance of Fe and {alpha}-elements both became ~ 1 solar within a factor of 2. This result relaxes the previous severe discrepancy between the ISM and stellar metallicities. The ISM metallicity in X-ray fainter galaxies is still uncertain, but we can at least constrain that the contribution from type-Ia SN to the ISM abundance is lower than in X-ray luminous systems. These results strongly suggest that a large fraction of SN Ia products have escaped into intergalactic space. Key words: galaxies: abundance - galaxies: ISM - X-rays: galaxies
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