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Are supernovae radio sources - A search for radio emission from young supernova remnantsA search has been conducted for radio emission at 11 and 3.7 cm from 46 recent supernovae having accurately determined positions and ages of a few months to 79 years. None of these supernovae was detected at a flux density greater than 5-10 mJy. These negative results cannot be explained by internal absorption and are thus due to intrinsically weak synchrotron emission in young supernova remnants. There are two possibilities: either (1) relativistic particles are accelerated not by the supernova outburst but by processes occurring much later (at least about 75 years) in the remnant or (2) the magnetic field in the young remnants evolves very slowly, in proportion to the inverse square root of time, so that its value in the remnants observed was no more than about 0.002 gauss. The constraints the observations place on these possibilities and on the energy in cosmic rays in young remnants are discussed. Gamma-ray observations at times of no more than about 1 year following an outburst will allow one to discriminate between the two alternative explanations of the radio results.
Document ID
19780042953
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Brown, R. L.
(National Radio Astronomy Observatory Green Bank, W. Va., United States)
Marscher, A. P.
(NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics, Greenbelt, Md.; National Radio Astronomy Observatory, Green, United States)
Date Acquired
August 9, 2013
Publication Date
March 1, 1978
Publication Information
Publication: Astrophysical Journal
Subject Category
Astronomy
Accession Number
78A26862
Distribution Limits
Public
Copyright
Other

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