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

ATel #2020; A. Bunthaler (MPIfR), K. M. Menten (MPIfR), M. J. Reid (CfA), C. Henkel (MPIfR), G. C. Bower (UC Berkeley), H. Falcke (Uni Nijmegen, ASTRON)
on 17 Apr 2009; 22:27 UT
Credential Certification: Andreas Brunthaler (brunthal@mpifr-bonn.mpg.de)

Tweet

We report the discovery of a new bright radio transient in M82's central region. Using the Very Large Array, we observed the nuclear region of M82 on 2008 March 24, 2008 May 03, and 2009 April 08 at 22 GHz and detected a new bright radio source. We find a flux density for this flaring source that is ~300 times larger than upper limits determined in previous observations. We estimated its position to be (J2000):

RA = 09h 55m 51.55s +/- 0.01s
DEC = +69d 40' 45.792'' +/- 0.005''

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 104 mJy on 2008 March 24, to 90 mJy on 2008 May 03, and 11 mJy on 2009 April 08. 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.

For more information see arxiv:0904.2388

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