scholarly journals The X-Ray Background in Isotropic World Models

1969 ◽  
Vol 22 (4) ◽  
pp. 521 ◽  
Author(s):  
AD Payne
Keyword(s):  
Characteristic Time ◽  
Cosmic Ray ◽  
Black Body ◽  
Black Body Radiation ◽  
Fast Electrons ◽  
X Ray ◽  
Intergalactic Space ◽  
Source Spectra ◽  
X Ray Background ◽  
The Universe

This paper is an attempt to describe the diffuse X-ray background in terms of Compton radiation from cosmic ray electrons in intergalactic space. Similarities between the X-ray and radio source spectra suggest that fast electrons escape more or less freely from radio galaxies. It is assumed that the time scale of electron injection is small compared with the characteristic time of evolution of the universe. The electrons are considered to lose energy through Compton scattering (due to the presence of the universal black-body radiation at 3�K) and by expansion of the coordinate system.

scholarly journals Diffuse cosmic X-rays from non-thermal intergalactic bremsstrahlung

1970 ◽  
Vol 37 ◽  
pp. 392-401
Author(s):  
Joseph Silk
Keyword(s):  
Cosmic Rays ◽  
Intergalactic Medium ◽  
Energy Requirement ◽  
Cosmic Ray ◽  
X Rays ◽  
Degree Of Ionization ◽  
X Ray ◽  
Normal Galaxies ◽  
X Ray Background ◽  
High Degree

The diffuse X-ray background between 1 keV and 1 MeV is interpreted as non-thermal bremsstrahlung in the intergalactic medium. The observed break in the X-ray spectrum at ∼40 keV yields the heat input to the intergalactic medium, the break being produced by ionization losses of sub-cosmic rays. Proton bremsstrahlung is found not to yield as satisfactory an agreement with observations as electron bremsstrahlung: excessive heating tends to occur. Two alternative models of cosmic ray injection are discussed, one involving continuous injection by evolving sources out to a redshift of about 3, and the other model involving injection by a burst of cosmic rays at a redshift of order 10. The energy density of intergalactic electrons required to produce the observed X-rays is ∼ 10−4 eV/cm3. Assuming a high density (∼ 10−5 cm−3) intergalactic medium, the energy requirement for cosmic ray injection by normal galaxies is ∼ 1058–59ergs/galaxy in sub-cosmic rays. The temperature evolution of the intergalactic medium is discussed, and we find that a similar energy input is also required to explain the observed high degree of ionization (if 3C9 is at a cosmological distance).

scholarly journals The X-Ray Background: Origin and Implications

1980 ◽  
Vol 92 ◽  
pp. 207-225
Author(s):  
Martin J. Rees
Keyword(s):  
Large Scale ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
X Ray Background ◽  
The Universe

This paper will be concerned with three topics relevant to the X-ray background: (i) X-ray emission mechanisms in quasars; (ii) the contributions to the X-ray background from quasars, clusters of galaxies, intercluster gas, young galaxies, etc; and (iii) the use of X-ray background observations as a probe for large-scale density irregularities in the Universe.

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