Diffuse x-ray background spectrum from 3 to 50 keV

Journal Article · Tue Jan 01 04:00:00 EST 1980 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/157601· OSTI ID:5661790

Marshall, F E; Boldt, E A; Holt, S S; Miller, R B; Mushotzky, R F; Rose, L A; Rothschild, R E; Serlemitsos, P J

The spectrum of the extragalactic diffuse X-ray background has been measured with the GSFC Cosmic X-Ray Experiment on HEAO 1 for regions of the sky away from known point sources and more than 20 /sup 0/ from the galactic plane. A total exposure of 80 m/sup 2/-s-sr is available at present. Free-free emission from an optically thin plasma of 40 +- 5 keV provides an excellent description of the observed spectrum from 3 to 50 keV. This spectral shape is confirmed by measurements from five separate layers of three independent detectors. With an estimated absolute precision of approx.10%, the intensity of the emission at 10 keV is 3.2 keV keV/sup -1/ cm/sup -2/ s/sup -1/ sr/sup -1/, a value consistent with the average of previously reported spectra. No other spectral features, such as iron line emission, are evident. This spectrum is not typical of known extra-galactic objects. A uniform hot intergalactic medium of approximately 36% of the closure density of the universe would produce such a flux, although nonuniform models indicating less total matter are probably more realistic.

• Research Organization: Laboratory for High Energy Astrophysics, NASA Goddard Space Flight Center
• OSTI ID: 5661790
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 235:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640103* -- Astrophysics & Cosmology-- Quasi-Stellar
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71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BACKGROUND RADIATION
COSMIC RADIATION
COSMIC RADIO SOURCES
COSMIC RAY DETECTION
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
COSMOLOGY
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ELECTROMAGNETIC RADIATION
GALAXIES
GALAXY CLUSTERS
IONIZING RADIATIONS
MEASURING INSTRUMENTS
PROPORTIONAL COUNTERS
QUASARS
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RADIATION DETECTORS
RADIATIONS
SPECTRA
X RADIATION
X-RAY GALAXIES
X-RAY SPECTRA