scholarly journals The Intergalactic Medium

1982 ◽  
Vol 97 ◽  
pp. 453-459
Author(s):  
A. C. Fabian ◽  
A. K. Kembhavi
Keyword(s):  
Radio Emission ◽  
Intergalactic Medium ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Intergalactic Gas ◽  
X Ray ◽  
Extended Radio ◽  
X Ray Background ◽  
Ngc 1275 ◽  
Intracluster Gas

The density of intergalactic gas may be an important parameter in the formation of extended radio sources. It may range from ∼ 0.1 particle cm−3 in the centres of some rich clusters of galaxies down to 10−8cm−3 or less in intercluster space. The possible influence of the intracluster gas surrounding NGC 1275 on its radio emission is discussed, and the possibility that a significant fraction of the X-ray background is due to a hot intergalactic medium is explored in some detail.

scholarly journals Intergalactic Gas

1974 ◽  
Vol 63 ◽  
pp. 13-30
Author(s):  
George B. Field
Keyword(s):  
Background Intensity ◽  
Clusters Of Galaxies ◽  
Intergalactic Gas ◽  
X Ray ◽  
Direct Observations ◽  
X Ray Background ◽  
Intracluster Gas

Evidence that rich clusters of galaxies contain hot (T = 108 K) intracluster gas is reviewed. Such gas contributes little to Ω (0.003) but it has been argued that Ω must be less than 0.05 for true intergalactic gas, if accretion of more gas than is observed in rich clusters is to be avoided. This argument is reviewed.If the de Vaucouleurs' groups are bound by intracluster gas, T is expected to be 105 to 107 K and the contribution to Ω is ≃ 1. Since the clumping factor C is estimated to be ≃ 7, the resulting value of Ω2C is ≃ 7. This does not violate the observed diffuse soft X-ray background intensity. Gas should be sought in such groups. Smoothly distributed gas with 107 < T < 3 × 108 K and Ω = 1 is not ruled out by direct observations.

scholarly journals Clusters with extended radio emission at high frequencies

1978 ◽  
Vol 79 ◽  
pp. 157-159
Author(s):  
R. Wielebinski
Keyword(s):  
Radio Emission ◽  
Direct Measurement ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Coma Cluster ◽  
Extended Source ◽  
High Frequencies ◽  
Extended Radio ◽  
Extended Component ◽  
Perseus Cluster

The existence of ‘haloes’ in clusters of galaxies was deduced by Ryle and Windram (1968) for the Perseus cluster and by Willson (1970) for the Coma cluster at 408 MHz by comparing total flux measured by a single dish with the sum of fluxes of radio sources found in the field. A direct measurement of the extended source Coma C was made by Jaffe et al. (1976) at 610 MHz. the failure to detect the halo of Coma at higher frequencies is attributed by all authors to a steep spectrum of this extended component.

scholarly journals Extended radio emission in clusters of galaxies: recent Westerbork observations

1978 ◽  
Vol 79 ◽  
pp. 153-155
Author(s):  
E.A. Valentijn ◽  
H. van der Laan
Keyword(s):  
Radio Emission ◽  
Galaxy Clusters ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Extended Radio

Whether galaxy clusters, in addition to a number of radio sources associated with individual cluster members, have an extended radio emitting region designated as cluster halo is in an interesting way related to several questions concerning cluster characteristics:

scholarly journals Detecting shocked intergalactic gas with X-ray and radio observations

2019 ◽  
Vol 627 ◽  
pp. A5 ◽  
Author(s):  
F. Vazza ◽  
S. Ettori ◽  
M. Roncarelli ◽  
M. Angelinelli ◽  
M. Brüggen ◽  
...  
Keyword(s):  
Large Scale ◽  
Intergalactic Medium ◽  
Thermal Emission ◽  
Intergalactic Gas ◽  
Radio Observations ◽  
X Ray ◽  
Large Scale Structures ◽  
Hot Gas ◽  
Scale Structures ◽  
Radio Band

Detecting the thermal and non-thermal emission from the shocked cosmic gas surrounding large-scale structures represents a challenge for observations, as well as a unique window into the physics of the warm-hot intergalactic medium. In this work, we present synthetic radio and X-ray surveys of large cosmological simulations in order to assess the chances of jointly detecting the cosmic web in both frequency ranges. We then propose best observing strategies tailored for existing (LOFAR, MWA, and XMM) or future instruments (SKA-LOW and SKA-MID, Athena, and eROSITA). We find that the most promising targets are the extreme peripheries of galaxy clusters in an early merging stage, where the merger causes the fast compression of warm-hot gas onto the virial region. By taking advantage of a detection in the radio band, future deep X-ray observations will probe this gas in emission, and help us to study plasma conditions in the dynamic warm-hot intergalactic medium with unprecedented detail.

Extragalactic X-ray sources and the diffuse X-ray background

1979 ◽  
Vol 366 (1726) ◽  
pp. 391-402 ◽  
Keyword(s):  
Spatial Distribution ◽  
Euclidean Space ◽  
Active Galaxies ◽  
Clusters Of Galaxies ◽  
Optical Identification ◽  
X Ray ◽  
Luminosity Functions ◽  
Sky Survey ◽  
Order Of Magnitude ◽  
X Ray Background

Results from the Ariel 5 sky survey instrument relating to the properties and the spatial distribution of extragalactic X-ray sources are discussed. The lg N -lg S relation for sources in the 2A catalogue is consistent with a uniform distribution of sources in Euclidean space. In addition, measure­ments of fluctuations in the X-ray background suggest that the Euclidean form of the source counts can be extrapolated to flux levels at least an order of magnitude fainter than the 2A catalogue limit. Information is also available from the optical identification of 2A sources which, through redshift measurements, enables the X-ray luminosity functions of the two main classes of source, namely clusters of galaxies and active galaxies, to be determined. The luminosity functions can be used to calculate the contribution of clusters of galaxies and active galaxies to the diffuse X-ray background in the 2-10 keV range. It is found that cosmological evolution of one or both populations is required to account for the diffuse X-ray background entirely in terms of the integrated emission from these sources.

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
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