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Properties of supernova remnant in nearby galaxy explored in radio continuum study

Using the Australia Telescope Compact Array (ATCA) and Parkes 64-m telescope, an international team of astronomers has performed a radio continuum study of MC SNR J0519–6902—a supernova remnant in the Large Magellanic Cloud (LMC). The new study, detailed in a paper April 16 on the preprint server arXiv, yields important insights into the properties of this remnant.

Supernova remnants (SNRs) are diffuse, expanding structures resulting from a supernova explosion. They contain ejected material expanding from the explosion and other interstellar material that has been swept up by the passage of the shockwave from the exploded star.

MC SNR J0519–6902 (also known as LHG 26) is a supernova remnant identified in the LMC in 1981. It has a diameter of about 26 light years and showcases a radio ring-like morphology with three bright regions.

Although many studies of MC SNR J0519–6902 have been conducted, many of its properties are uncertain as there is significant discrepancy in the available data. For instance, the estimated age of this SNR, based on various observations, varies between 450 and 1,500 years. It is assumed that MC SNR J0519–6902 is a result of a type Ia supernova explosion and the mass of the progenitor star is estimated to be between 1.2 and 4.0 solar masses.

Therefore, in order to put more constraints on the properties of MC SNR J0519–6902, a group of astronomers led by Rami Z. E. Alsaberi of the Gifu University in Japan decided to investigate this SNR with ATCA and Parkes telescope. Their study was complemented by the data from the Hubble Space Telescope and the Chandra X-ray observatory.

The observations found that MC SNR J0519–6902 has an average fractional polarization of approximately 5 and 6 percent at 5,500 and 9,000 MHz, respectively. Therefore, its polarization is similar to that of younger SNRs like N 103B in LMC or G1.9+0.3 in the Milky Way galaxy.

Furthermore, it was found that MC SNR J0519–6902 has a spectral index at a level of -0.62, which is similar to spectral indices of other younger remnants, including Kepler's SNR and SN 1006.

When it comes to the magnetic field strength of MC SNR J0519–6902, it was estimated to be between 10 and 100 µG. Hence, this value is also similar to younger remnants, including Kepler's SNR.

According to the authors of the paper, the new results generally indicate that MC SNR J0519–6902 is a young remnant that may be at the end of its free expansion phase.

"MC SNR J0519–6902 position at Σ–D tracks can set it somewhere at the end of the free expansion phase, close to entering the early Sedov phase of evolution," the researchers concluded.