TY - JOUR
T1 - A hot helium plasma in the Galactic center region
AU - Belmont, R.
AU - Tagger, M.
AU - Muno, M.
AU - Morris, M.
AU - Cowley, S.
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 2005/9/20
Y1 - 2005/9/20
N2 - Recent X-ray observations by the space mission Chandra confirmed the astonishing evidence of a diffuse, hot, thermal plasma at a temperature of ∼9 × 107 K (∼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.
AB - Recent X-ray observations by the space mission Chandra confirmed the astonishing evidence of a diffuse, hot, thermal plasma at a temperature of ∼9 × 107 K (∼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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U2 - 10.1086/497139
DO - 10.1086/497139
M3 - Article
AN - SCOPUS:27744512975
VL - 631
SP - L53-L56
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1 II
ER -