Second radio relic discovered in the galaxy cluster Abell 2108

Astronomers from India and Taiwan have used the upgraded Large Metrewave Radio Telescope (uGMRT) to carry out radio observations of a galaxy cluster referred to as Abell 2108. Consequently, they detected a second radio relic, which is way bigger and differs in morphology from the beforehand recognized relic on this cluster. The discovering was reported in a paper published Dec. 7 on the pre-print server arXiv.

Radio relics are diffuse, elongated radio sources of synchrotron origin. They happen within the type of spectacular single or double symmetric arcs on the peripheries of galaxy clusters. Astronomers are particularly within the seek for double relics as such options may present essential details about cluster mergers and the resultant emission.

At a redshift of 0.09, Abell 2108 (or A2108 for brief) is a galaxy cluster with an estimated mass of about 301 trillion solar masses. Earlier observations have discovered that the cluster hosts a radio relic in its southwestern area with dimensions of about 980,000 by 390,000 light years.

Now, a crew of astronomers led by Swarna Chatterjee of the Indian Institute of Know-how Indore, India, report the invention of one other radio relic in Abell 2108, which makes it considered one of only some low-mass galaxy clusters with double radio relics.

“On this paper, we report the invention of a brand new relic within the northeast of low-mass galaxy cluster A2108 and make sure the presence of the opposite relic within the southwest with increased significance utilizing uGMRT band-3,” the researchers wrote.

Initially, Chatterjee’s crew noticed a definite diffuse emission characteristic within the northeastern periphery of Abell 2108. The brightest area of this characteristic was measured to be about 1.4 million gentle years away from the cluster‘s X-ray middle. The situation and morphology of the emission point out that it’s a radio relic.

The newfound radio relic showcases a patchy construction, differing in morphology from the identified one, and can also be a lot bigger—it spans over a area of two by a million years. The northeastern relic has an built-in flux density of 24.8 mJy, subsequently greater than two instances increased than the southwestern one.

The observations discovered that each radio relics in Abell 2108 have significantly low radio energy extrapolated to 1.4 GHz, when in comparison with different double relic clusters. Furthermore, the outcomes point out that the floor brightness ratio of the 2 relics differs, which means that they might not have the identical origin.

The astronomers additionally detected the presence of floor brightness soar and tentative temperature soar within the midst of the northeastern radio relic, indicative of a weak supersonic shock. This might clarify the low radio luminosity of the newfound relic.

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