X-Ray Spectrum of 'the Cap' of M82(Chapter 3. Chemical Structure and Evolution Clusters of Galaxy, The Extreme Universe in the Suzaku Era)

概要

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The extended X-ray emission from 'the Cap' region located 11.6kpc above the disk of the starburst galaxy M82 has been observed with Suzaku and XMM-Newton. We have clearly detected K-shell emission lines from O VII, O VIII, Ne X, Mg XI, Mg XII and the Fe-L complex. Two optically-thin thermal plasma components are required to fit the observed X-ray spectra. We have determined the metal abundances of O, Ne, Mg, Si and Fe in this region for the first time. Their metal abundance ratios agree well with those of metal-poor stars and the model prediction of metals synthesized by type-II supernovae, but are inconsistent with those of type-Ia supernovae. This result is support for the idea that the origin of the metals in the Cap is type-II supernovae explosions occurring in the starburst regions in the M82 galaxy. We discuss the contribution from sputtered dust grains to the metals in the Cap and suggestion of the charge-exchange processes. We also report the detection of hard X-ray emission above 2keV extending from M82 along the north-east and north-west directions.
理論物理学刊行会の論文
2007-12-19