Publication Date:
2009-05-02
Description:
An unresolved X-ray glow (at energies above a few kiloelectronvolts) was discovered about 25 years ago and found to be coincident with the Galactic disk-the Galactic ridge X-ray emission. This emission has a spectrum characteristic of a approximately 10(8) K optically thin thermal plasma, with a prominent iron emission line at 6.7 keV. The gravitational well of the Galactic disk, however, is far too shallow to confine such a hot interstellar medium; instead, it would flow away at a velocity of a few thousand kilometres per second, exceeding the speed of sound in the gas. To replenish the energy losses requires a source of 10(43) erg s(-1), exceeding by orders of magnitude all plausible energy sources in the Milky Way. An alternative is that the hot plasma is bound to a multitude of faint sources, which is supported by the recently observed similarities in the X-ray and near-infrared surface brightness distributions (the latter traces the Galactic stellar distribution). Here we report that at energies of approximately 6-7 keV, more than 80 per cent of the seemingly diffuse X-ray emission is resolved into discrete sources, probably accreting white dwarfs and coronally active stars.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Revnivtsev, M -- Sazonov, S -- Churazov, E -- Forman, W -- Vikhlinin, A -- Sunyaev, R -- England -- Nature. 2009 Apr 30;458(7242):1142-4. doi: 10.1038/nature07946.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Excellence Cluster Universe, Technische Universitat Munchen, 85748, Garching, Germany. mikej@mpa-garching.mpg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19407795" target="_blank"〉PubMed〈/a〉
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
