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Ball et al. have used data from the pilot observations of the
EMU/POSSUM surveys to study the "missing supernova remnant (SNR)
problem" -- the discrepancy between the number of Galactic SNRs that
have been observed and the number that are estimated to exist.
In a pilot survey field containing the plane of our Galaxy,
the team found 7 known SNRs and 21 SNR
candidates, of which 13 have not been previously studied.
The image above shows
933 MHz images of three of the new SNR candidates,
with Galactic longitude on the x-axis and Galactic latitude on the y-axis.
G324.3+0.2 (left) has a shell structure
that is almost perfectly circular, with some brightening towards the
southeast. Based on the distinct morphology and clear lack of an
MIR counterpart, this is a strong candidate for classification as
an SNR. A large, bright HII region can be seen to the right (west) of the
source.
G324.4−0.4 (centre) is an elliptical shell with brightening
along the southwest edge. There are many overlapping point sources
and a couple of known HII regions located to the northeast. There is
overlapping emission in the MIR but nothing that clearly mirrors the
shell structure seen in the radio.
G324.4−0.2 (right) is a very small, faint
shell-like structure with an overlapping point source. It is located just
north of G324.4−0.4 and can also be seen in the central image. There is no
obvious MIR counterpart, supporting the identification as an SNR.
The results of this paper
demonstrate the potential of the full EMU/POSSUM surveys to uncover
more of the missing Galactic SNR population.
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