High-latitude H I structure and the soft X-ray background

Data from the UHURU satellite have provided a list of more than forty high latitude sources (|b| > 20°). X-rays have been detected from among the nearest normal galaxies, giant radio galaxies, Seyferts, QSOs and clusters of galaxies. The cluster sources appear to be extended by several hundred kiloparsecs as well as being very luminous. These cluster sources have systematic differences in their X-ray spectra from individual galaxies.About twenty sources are not reliably identified so far. A few of these are located near undistinguished 3C or MSH radio sources. The rest are either located near distant clusters or undistinguished bright galaxies, or are too far south, so that we have not sufficient optical data to allow a thorough search for possible association with clusters or unusual individual galaxies.The luminosity function for weak, high latitude X-ray sources is determined, and the contribution of sources just below the UHURU threshold of detectability to observed fluctuations in the diffuse X-ray background is evaluated. The total contribution of all observed types of extragalactic sources to the X-ray background is estimated.

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Ariel results on extragalactic X-ray sources

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1976.0120 ◽

1976 ◽

Vol 350 (1663) ◽

pp. 491-503 ◽

Cited By ~ 12

Keyword(s):

High Latitude ◽

Field Of View ◽

Potential Contribution ◽

Galactic Latitude ◽

Survey Experiment ◽

Spectral Measurements ◽

High Galactic Latitude ◽

X Ray ◽

X Ray Background ◽

The University

Two of the instruments on Ariel 5 are designed to study the weak high galactic latitude X-ray sources, a number of which have been identified with extragalactic objects. The survey experiment of the University of Leicester has detected sources with strengths down to 2-3 Uhuru counts. Several high latitude sources catalogued by Uhuru have apparently dropped in intensity below this level and improved positions have been obtained for other high latitude sources which support the tentative identification with optical counterparts. The pointed instrument from M. S. S. L. has a programme of spectral measurements of identified extragalactic and other weak sources at high galactic latitudes. The field of view of the M. S. S. L. experiment makes the instrument well suited to the study of the diffuse X-ray background. Results are presented from both experiments on a number of the extragalactic sources and, in particular, discussed in relation to their potential contribution to the diffuse X-ray background. Preliminary measurements of the diffuse X-ray background by the M. S. S. L. instruments are presented.

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