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Limiting Brightness Temperature for Synchrotron Sources

Published online by Cambridge University Press:  12 April 2016

A. Lähteenmäki
Affiliation:
Metsähovi Radio Research Station, Helsinki University of Technology, Finland
E. Valtaoja
Affiliation:
Tuorla Observatory, University of Turku, Finland

Abstract

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The maximum brightness temperature limit for synchrotron sources derived from inverse Compton catastrophe is usually taken to be 1012 K. Readhead has argued in 1994 that the equipartition brightness temperature may be a better estimate for Tb,lim. It provides a value of 5 × 1010 K. We suggest that a reasonable estimate of the value of Tb,lim can also be achieved by comparing Doppler boosting factors from total flux density variations at 22 and 37 GHz with traditional Doppler factors from the SSC X-ray flux. We also compare our variability brightness temperatures with values calculated for individual sources observed with VLBI, obtaining other independent estimates of Tb,lim.

Type
Research Article
Copyright
Copyright © Astronomical Society of the Pacific 1998

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