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A Hot Helium Plasma in the Galactic Center Region

Abstract : Recent X-ray observations by the space mission Chandra confirmed the astonishing evidence for a diffuse, hot, thermal plasma at a temperature of 9. $10^7$ K (8 keV) found by previous surveys to extend over a few hundred parsecs in the Galactic Centre 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 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 this opens by discussing the origin of this gas, and by suggesting possible heating mechanisms.
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Contributor : Simone Lantz <>
Submitted on : Friday, November 25, 2005 - 3:13:02 PM
Last modification on : Wednesday, October 21, 2020 - 4:32:14 PM

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R. Belmont, Michel Tagger. A Hot Helium Plasma in the Galactic Center Region. The Astrophysical Journal, American Astronomical Society, 2005, 631, pp.L53-L56. ⟨in2p3-00025131⟩



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