MeerKAT total power image of one of the SNRs studied, designated G4.2−3.5, at 1335 MHz in galactic coordinates. Credit: arXiv (2023). DOI: 10.48550/arxiv.2311.12140
Using the MeerKAT radio telescope, astronomers at the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, and elsewhere studied a batch of 36 high-latitude supernova remnants. Results of the observation campaign, published on November 20 on the pre-print server arXivprovide important information on the properties of these remains.
Supernova remnants (SNR) are expansive, diffuse formations formed following the explosion of a supernova. They house 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 crucial 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 (ISM). SNRs are also believed to be responsible for the acceleration of galactic cosmic rays.
Recently, a team of astronomers led by NRAO’s William Cotton chose 36 little-studied galactic SNRs to observe with MeerKAT, with the primary goal of shedding light on their properties.
“We present comprehensive Stokes MeerKAT L band observations (856-1712 MHz) of 36 high-latitude supernova remnants,” the researchers wrote in the paper.
The observations revealed that two of the 36 observed sources are not SNRs. The object designated G30.7−2.0, initially classified as SNR, is a structure composed of three relatively bright background sources appearing to form an arc. The second, G15.1−1.6, appears to be more likely a region of ionized interstellar atomic hydrogen (HII).
The images show that at least half of the SNRs studied have flares or protrusions. Most eruptions seem to indicate that something is breaking through the outer edge of the rest’s shell. The astronomers noted that this discovery was only possible thanks to the unprecedented sensitivity and high fidelity of the extended emission MeerKAT images, as most of these flares show extremely low radio surface brightness.
The study allowed researchers to explore the magnetic fields of the SNR sample. For example, they found that the magnetic field inside the G327.6+14.6 remnant had a largely radial magnetic field, while the G4.8+6.2 SNR had a mostly tangential magnetic field, except in the regions of eruption where it is radial.
Astronomers also found that several of the supernova remnants studied had a bilateral or barrel-shaped structure. Such structures are ubiquitous in mature SNRs.
“Mature SNRs typically exhibit a bilateral or barrel-shaped structure, indicative of expansion within an approximately uniform ambient medium with a relatively uniform magnetic field,” the paper’s authors explain.
More information:
William Cotton et al, MeerKAT 1.3 GHz observations of supernova remnants, arXiv (2023). DOI: 10.48550/arxiv.2311.12140
Journal information:
arXiv
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Quote: Astronomers inspect supernova remnants with MeerKAT (November 30, 2023) retrieved December 1, 2023 from
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