Discovery of a bright radio transient in M82: a new radio supernova?

Abstract

In this Letter, we report the discovery of a new bright radio transient in M82. Using the Very Large Array, we observed the nuclear region of M82 at several epochs at 22 GHz and detected a new bright radio source in this galaxy's central region. We find a flux density for this flaring source that is ~300 times larger than upper limits determined in previous observations. The flare must have started between 2007 October 29 and 2008 March 24. Over the last year, the flux density of this new source has decreased from ~100 mJy to ~11 mJy. The lightcurve (based on only three data points) can be fitted better with an exponential decay than with a power law. Based on the current data we cannot identify the nature of this transient source. However, a new radio supernova seems to be the most natural explanation. With it's flux density of more than 100 mJy, it is at least 1.5 times brighter than SN1993J in M81 at the peak of its lightcurve at 22 GHz.

accepted Astronomy & Astrophysics, 4 pages, 3 figures, final version & corrected abstract, also available at http://www.mpifr-bonn.mpg.de/staff/abrunthaler/pub.shtml

References in corpus (6)

• Long Term Radio Monitoring of SN 1993J
• Deep MERLIN 5GHz Radio Imaging of Supernova Remnants in the M82 Starburst
• The Proper Motion of the Local Group Galaxy IC 10
• SN 1993J VLBI (IV): A Geometric Determination of the Distance to M81 with the Expanding Shock Front Method
• 15 years of VLBI observations of two compact radio sources in Messier 82
• The Ultraluminous X-ray Sources near the Center of M82

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• ASGARD: A Large Survey for Slow Galactic Radio Transients. I. Overview and First Results
• SPIRITS 15c and SPIRITS 14buu: Two Obscured Supernovae in the Nearby Star-Forming Galaxy IC 2163
• The radio evolution of supernova SN2008iz in M82
• X-ray supernova remnants in the starburst region of M82
• Origin of the diffuse 4-8 keV emission in M82