Composite RGB image of G321.3–3.9 as seen in the eROSITA eRASS:4 sky surveys and the MWA radio image taken at 200 MHz. Credit: Mantovanini et al., 2024.
Astronomers from Curtin University in Australia and elsewhere report the detection of a new supernova remnant (SNR) located about 3,300 light years away. The new SNR, designated G321.3-3.9, has an elliptical shape and is estimated to be a few thousand years old. The discovery was detailed in a paper published January 30 on the preprint server. arXiv.
SNRs are diffuse, expanding structures resulting from a supernova explosion. They contain ejected material from the explosion and other interstellar material that was swept away by the passage of the shock wave from the exploded star.
The study of supernova remnants is important to astronomers because they play a key role in the evolution of galaxies, dispersing the heavy elements produced during the supernova explosion and providing the energy necessary for heating the interstellar medium . SNRs are also believed to be responsible for the acceleration of galactic cosmic rays.
The extended source G321.3-3.9 was classified as an SNR candidate in 1997. Previous observations revealed that it is an elliptical and almost complete shell with a size of 109 × 64 arcmin.2maximum flux of 10 mJy/beam and total integrated flux density greater than 0.37 Jy.
Today, a team of astronomers led by Silvia Mantovanini from Curtin University analyzed a wealth of radio and X-ray data from various surveys as well as the Spektr-RG spacecraft, confirming the SNR status of G321 .3-3.9.
According to the study, G321.3-3.9 shows an extended structure at low X-ray energies surrounded by a radio shell and exhibits no diffuse infrared emissions. The spectral index of the source was measured to be -0.8, which is consistent with non-thermal synchrotron emission in accordance with a shell-type SNR.
Based on the data collected, researchers estimate that G321.3-3.9 is between 2,300 and 3,300 light years away. Distance estimates suggest that the SNR has a diameter of approximately 62 to 97 light years and is between 1,700 and 4,000 years old. Therefore, the assumed age is younger than the shell shape and low brightness at radio frequencies would suggest.
The astronomers note that these uncertainties are due to the limited statistics of photons in X-rays and the lack of association between the shell and a known pulsar. They add that none of the pulsars located in the same region have an age or proper motion that could be linked to a supernova remnant the size of G321.3-3.9.
“We will carry out PARKES follow-up observations inside the remaining shell in the radio band to look for a possible pulsar association. Successful detection of the pulsations would allow calculation of the dispersion measure and therefore the age and distance at which G321.3-3.9 is located, as well as its expansion rate,” the scientists explained.
More information:
S. Mantovanini et al, G321.3-3.9: a new supernova remnant observed with multi-band radio data and in the SRG/eROSITA All-Sky surveys, arXiv (2024). DOI: 10.48550/arxiv.2401.17294
Journal information:
arXiv
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