Quasi-stellar objects in the intergalactic medium - Source for the cosmic X-ray background

1980 ◽  
Vol 238 ◽  
pp. 794 ◽  
Author(s):  
R. D. Sherman
Keyword(s):  
Intergalactic Medium ◽  
Stellar Objects ◽  
X Ray ◽  
Quasi Stellar Objects ◽  
X Ray Background

scholarly journals The X-ray emission of a hot dense intergalactic plasma

1970 ◽  
Vol 37 ◽  
pp. 377-381
Author(s):  
J. Bergeron
Keyword(s):  
Cosmological Constant ◽  
Emission Spectra ◽  
Intergalactic Gas ◽  
Degree Of Ionization ◽  
Stellar Objects ◽  
X Ray ◽  
Points Of Interest ◽  
Quasi Stellar Objects ◽  
X Ray Background

The implications of the existence of a dense, hot, intergalactic plasma are discussed for friedman universes with a zero cosmological constant. The points of interest are the temperature of the intergalactic gas and the degree of ionization of its constituents. The soft X-ray emission of this dense intergalactic gas must be in agreement with the actual observations of isotropic X-ray background around 1–3 keV and 0.27 keV. Moreover the model cannot be in contradiction with the lack of Lyman α absorption in the emission spectra of the quasi-stellar objects.

scholarly journals The X-ray properties of high redshift quasi-stellar objects

1986 ◽  
Vol 119 ◽  
pp. 247-252
Author(s):  
Scott F. Anderson ◽  
Bruce Margon
Keyword(s):  
Background Radiation ◽  
High Redshift ◽  
Galactic Latitude ◽  
X Rays ◽  
Stellar Objects ◽  
High Galactic Latitude ◽  
X Ray ◽  
Quasi Stellar Objects ◽  
X Ray Background ◽  
Intermediate Redshift

We describe a program aimed at characterizing the X-ray emission of high redshift QSOs. We have obtained slitless spectra of 50 high galactic latitude fields previously imaged at very high levels of sensitivity by the Einstein Observatory, generally for original goals unrelated to QSOs. Our survey, covering ∼ 17 deg2 of sky to limiting magnitude Bcont ∼ 21, has yielded ∼ 400 previously uncatalogued QSO candidates, each with sensitive new X-ray information available. About 100 of these objects, constituting a “high confidence” set of QSOs, chiefly in the redshift range 1.7 < z < 3 and thus complementary to previous samples with X-ray data, are used to derive the X-ray properties of high redshift QSOs. Even at these most sensitive available X-ray flux levels, only about 25% of the objects are positively detected in X-rays; thus extensive attention has been given to proper treatment of the upper-limit information. We find a mean optical-to-X-ray slope parameter for the sample of . Our results are combined with those of previous surveys to estimate the fraction of the diffuse X-ray background radiation due to QSOs. QSOs are capable of supplying the majority of the radiation, but the chief contribution comes from an annulus of intermediate redshift, moderate luminosity objects.

The properties of the dusty inner regions of nearby QSOs

2019 ◽  
Vol 15 (S356) ◽  
pp. 95-95
Author(s):  
Itziar Aretxaga
Keyword(s):  
Star Formation ◽  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Stellar Objects ◽  
X Ray ◽  
Mir Spectroscopy ◽  
Polycyclic Aromatic ◽  
Quasi Stellar Objects

AbstractWe present MIR spectroscopy and photometry obtained with CanariCam on the 10.4 m Gran Telescopio CANARIAS for a sample of 20 nearby, MIR bright and X-ray luminous quasi-stellar objects (QSOs). We find that for the majority of QSOs the MIR emission is unresolved at angular scales ∼0.3 arcsec. We derive the properties of the dusti tori that surround the nucleus based on these observations and find significant differences in the parameters compared with a sample of Seyfert 1 and 2 nuclei. We also find evidence for polycyclic aromatic hydrocarbon (PAH) features in the spectra, indicative of star formation, more centrally peaked (on scales of a few hundred pc) than previously believed.

scholarly journals Heating and Ionization of the Intergalactic Medium by an Early X‐Ray Background

2001 ◽  
Vol 563 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Aparna Venkatesan ◽  
Mark L. Giroux ◽  
J. Michael Shull
Keyword(s):  
Intergalactic Medium ◽  
X Ray ◽  
X Ray Background

The X-ray properties of high-redshift quasi-stellar objects

1987 ◽  
Vol 314 ◽  
pp. 111 ◽  
Author(s):  
Scott F. Anderson ◽  
Bruce Margon
Keyword(s):  
High Redshift ◽  
Stellar Objects ◽  
X Ray ◽  
Quasi Stellar Objects

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 On the Nature of Soft X‐Ray Weak Quasi‐stellar Objects

2000 ◽  
Vol 528 (2) ◽  
pp. 637-649 ◽  
Author(s):  
W. N. Brandt ◽  
A. Laor ◽  
Beverley J. Wills
Keyword(s):  
Stellar Objects ◽  
X Ray ◽  
Quasi Stellar Objects
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