THE ISOTROPIC COSMIC GAMMA-RAY BACKGROUND WITH SMM
Given the Solar Maximum Mission (SMM) Gamma-Ray Spectrometer's
(GRS) nine years of exposure and large field of view, its data
contain a tremendously significant signal from the isotropic
cosmic gamma-ray background (CGB) in the energy range 0.3 - 8.0
MeV. We have extracted this signal by modeling its modulation by
the Earth's motion through the GRS field of view, along with
several other background components such as from the SAA and
Earth Albedo gamma rays.
We can quantify the success of the technique and evaluate
possible systematic errors because we have many independent
measurements of the CGB, which should be constant in time, and
and because all known other background components have narrow
lines that should not be present in the CGB. We find reasonably
good agreement between two different analysis methods. We compare
the CGB spectrum with line emission from iron production in
thermonuclear supernovae, and conclude that some other source(s)
must dominate the 1 MeV region.
File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 09:18.