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5th of May 2020
Supernova Remnants in M83
by Russell et al.
There are over 320 Supernova Remnants (SNRs) are known in our Galaxy, most of which were first identified as radio sources. However, far more SNRs are known in external galaxies, and most of these were discovered optically. M83 it is a relatively nearby (15 million light-years), nearly face-on, spiral galaxy with a starburst nuclear region and active star formation throughout its spiral arm structure. It has hosted six historically recorded supernovae within the past century probably plus another that was not detected at the time. More than 300 SNRs have been identified in M83, more than for any other external galaxy, and X-ray counterparts to over 85 of these SNRs have been detected.

Russell et al. have presented a new catalogue of radio sources in the face-on spiral galaxy M83. Radio observations taken with the Australia Telescope Compact Array (ATCA) at 5.5 and 9 GHz have detected 270 radio sources. Although a small number of these sources are background extragalactic sources, most are either H II regions or supernova remnants (SNRs) within M83 itself. Three of the six historical supernovae are detected, as is the previously reported very young remnant which is likely the result of a supernova that exploded in the last ~100 years but was missed. All of these objects are generally fading with time. Source confusion limits the ability to measure the radio emission from a number of the SNRs in M83, but 64 were detected in unconfused regions. A number of the radio sources are coincident with X-ray sources in M83; most of these coincident sources turn out to be supernova remnants.

The images aboves show multiwavelength imagery for SN1957D, one of the historical M83 supernovae that show radio emission. The four panels show Hubble Space Telescope WFC3 subtracted emission lines (Hα red, [S ii] green, [O iii] blue); HST WFC3 continuum (I band red, V band green, B band blue), Chandra X-ray (soft red, medium green, hard blue), and the ATCA detection image. The yellow circles are 4 arcseconds in diameter. More details are given in the paper, to be published in Monthly Notices of the Royal Astronomical Society.

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