期刊
ASTROPHYSICAL JOURNAL
卷 631, 期 1, 页码 L53-L56出版社
IOP PUBLISHING LTD
DOI: 10.1086/497139
关键词
galaxy : abundances; galaxy : center; ISM : abundances; ISM : magnetic fields; plasmas; X-rays : ISM
Recent X-ray observations by the space mission Chandra confirmed the astonishing evidence of a diffuse, hot, thermal plasma at a temperature of similar to 9 x 10(7) K (similar to 8 keV) that was found by previous surveys to extend over a few hundred parsecs in the Galactic center region. This plasma coexists with the usual components of the interstellar medium, such as cold molecular clouds and a soft (0.8 keV) component produced by supernova remnants, and its origin remains uncertain. First, simple calculations using a mean sound speed for a hydrogen-dominated plasma have suggested that it should not be gravitationally bound, and thus it requires a huge energy source to heat it in less than the escape time. Second, an astrophysical mechanism must be found to generate such a high temperature. No known source has been identified to fulfill both requirements. Here we address the energetics problem and show that the hot component could actually be a gravitationally confined helium plasma. We illustrate the new prospects that this opens up by discussing the origin of this gas and by suggesting possible heating mechanisms.
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