| 10th of May 2024 |
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| ASKAP Discovery of a new Galactic SNR Candidate |
| by Lazarević et al. |
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Supernova remnants (SNRs) are the resultant expanding structures that
remain after the death of massive stars in a supernova (SN)
explosion. It is generally accepted that the population of known
Galactic SNRs, which numbers around 300, vastly underrepresents the
expected population and the discovery of new Galactic SNRs is vital in
filling this knowledge gap.
Lazarević et al. report the discovery with ASKAP of a new Galactic
supernova remnant (SNR) candidate G308.73+1.38, which they name
Raspberry.
The SNR was serendipitously discovered in an ASKAP EMU (Evolutionary
Map of the Universe) survey observation in December 2023, made
at the central frequency of 943.4 MHz. Raspberry is proposed as a new
Galactic shell-type SNR based primarily on its radio morphology. WISE
(Wide-Field Infrared Survey Explorer) all-sky maps were searched and
no infrared emission that spatially corresponds with the observed
radio shell was found. This lack of infrared emission indicates that
the radio shell is purely non-thermal, formed by synchrotron emission
from ultra-relativistic particles energized by the expanding shock
front, typical of a shell-type SNR.
Additionally, a Stokes-V (circular polarisation) point source is found
close to the center of the SNR. This point source may be the remaining
compact source, a neutron star, or possibly a pulsar, formed during
the initial supernova event.
The image above is a RGB composite image where the total intensity map of Raspberry, observed by ASKAP at 944 MHz, is in red and blue while the WISE 12 μm infrared image is in green. The inset is the ASKAP Stokes-V zoomed-in image showing the possible progenitor source. |