X-Ray Study of Normal Galaxies with Ginga
Results from X-ray observations of nearby normal galaxies with the X-ray astronomy satellite Ginga are presented. X-ray spectra in the energy range 2-20 keV were obtained for the first time from four spiral (M31, M33, M51 and M81), three starburst (M82, M83 and NGC 253), and three elliptical (NGC 4472, NGC 4636 and NGC 3998) galaxies. M51 and NGC 3998 showed a power-law spectrum suggesting the presence of an active nucleus, while the others exhibited a thermal spectrum with kT ≤ 2 keV for elliptical galaxies and kT ≥ 4 keV for others. Iron emission line was weak or not significant for all spiral and starburst galaxies. Presence of a large extended X-ray emission (~ 2° in full width) around M82 was strongly suggested, which could be a large-scale halo formed by the mass ejection from M82.
KeywordsSpiral Galaxy Elliptical Galaxy Active Nucleus Iron Line Iron Abundance
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