Diffuse Soft X-ray Background
The Diffuse Soft X-ray Background ( German diffuse soft X-ray background ) is an irregularly distributed radiation in the range of low - energy X-rays of less than 10 keV . It is mainly caused by plasma with temperatures of more than 1,000,000 Kelvin in the plain and the halo of the Milky Way .
The distribution of the diffuse soft x-ray background depends on the wavelength. In the range of 100 eV the spatial distribution is inversely correlated to the density of neutral hydrogen from radio observations. The distribution is often compared to that of a Swiss cheese, with individual holes appearing on an approximately even continuum. In the band of 750 eV, individual objects appear along the galactic level , combined with a granular structure at higher galactic latitudes. The spectral distribution below 500 eV is typical for blackbody radiation . The soft, diffuse X-ray background was already described by the first X-ray satellites in the early 1960s, but the analysis of their components required a higher spectral and spatial resolution.
Today it is believed that the Diffuse Soft X-ray Background consists of the following components:
- old supernova remnants , where the X-rays are caused by the expanding gases of supernovae like the local bubble
- Shock fronts caused by stellar winds from hot early stars like the Wolf-Rayet stars . The two sources occur preferentially in the galactic plane and have characteristic diameters of around 100 parsecs
- Plasma clouds in the halo of the Milky Way, accelerated into the halo by supernova explosions from the galactic plane
- incident extragalactic gas that interacts with the interstellar matter of the Milky Way
- X-rays from the halos of other galaxies or galaxy clusters
- X-ray radiation from extragalactic sources diffracted by Thomson scattering
- unresolved active galactic cores from background galaxies
- Interaction of charged particles of the solar wind with the interstellar matter in the heliosphere
- the Warm-Hot Intergalactic Medium
- unresolved X-rays from the coronae of magnetically active stars such as the RS Canum Venaticorum stars
literature
- David B. Henley, Robin L. Shelton: Is the Milky Way's Hot Halo Convectively Unstable? In: Astrophysics. Solar and Stellar Astrophysics . 2014, arxiv : 1401.8016v1 (English).
- A. Gupta, M. Galeazzi, D. Koutroumpa, R. Smith, R. Lallement: Properties of the Diffuse X-ray Background toward MBM20 with Suzaku . In: Astrophysics. Solar and Stellar Astrophysics . 2009, arxiv : 0910.3971v1 (English).
- D. Koutroumpa, F. Acero, R. Lallement, J. Ballet, V. Kharchenko: OVII and OVIII line emission in the diffuse soft X-ray background: heliospheric and galactic contributions . In: Astrophysics. Solar and Stellar Astrophysics . 2007, arxiv : 0709.2260v1 (English).
- AM Soltan: The diffuse X-ray background . In: Astrophysics. Solar and Stellar Astrophysics . 2003, arxiv : astro-ph / 0309102v1 (English).
- KD Kuntz, SL Snowden: On the Contribution of Unresolved Galactic Stars to the Diffuse Soft X-ray Background . In: Astrophysics. Solar and Stellar Astrophysics . 2001, arxiv : astro-ph / 0102206v1 (English).