![\"Galaxy](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/07\/galaxy-cluster-abell-3.jpg\" "\\"Composite")
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Composite image of the Abell 3558 environment. Credit: arXiv (2025). DOI: 10.48550\/arxiv.2507.07549<\/p>\n
An international team of astronomers has performed multi-band radio observations of diffuse radio emission in a galaxy cluster known as Abell 3558. As a result, the observational campaign detected that the cluster hosts a peculiar mini-halo. The finding was detailed in a paper published<\/a> July 10 on the arXiv preprint server .<\/p>\n The largest known gravitationally-bound structures in the universe are galaxy clusters, which contain up to thousands of galaxies bound together by gravity. They form through accretion of mass and infall of smaller sub-structures and therefore could serve as excellent laboratories for studying galaxy evolution and cosmology.<\/p>\n Abell 3558, or A 3558 for short, is a massive galaxy cluster<\/a> at a redshift of approximately 0.047. It has a dynamical mass of about 1.48 quadrillion solar masses<\/a> and a bolometric X-ray luminosity at a level of 700 tredecillion erg\/s.<\/p>\n Previous observations of Abell 3558 have found that its intracluster medium showcases mixed characteristics and detected a significant large-scale diffuse radio emission in the cluster center. A group of astronomers led by Keegan Trehaeven of the Rhodes University in South Africa decided to take a closer look at this emission, with the aim of disentangling its origin. For this purpose, they employed the MeerKAT radio telescope and the Upgraded Giant Metrewave Radio Telescope (uGMRT).<\/p>\n “Here we present a detailed study of the diffuse radio emission at the center of A 3558 using deep observations carried out with MeerKAT UHFband (816 MHz) and uGMRT Band3 (400 MHz), complemented by the MeerKAT L-band (1,283 MHz) and ASKAP (887 MHz) data,” the researchers wrote in the paper.<\/p>\n The observations conducted by Trehaeven’s team found that the diffuse radio emission in the center of Abell 3558 has a radio power of 68 ZW\/Hz at 1.4 GHz and is more extended than previously thought. They identified a faint northern extension of this emission beyond the innermost cold front. This finding increases the projected largest linear size of the radio emission to about 1.8 million light years.<\/p>\n The study found that the investigated emission has an integrated spectral index of 1.18. The spectral index map shows a region of flatter spectrum just inside the X-ray cold front, which suggests a local turbulent re-acceleration. Beyond that, a region of steeper spectrum is observed, filling an X-ray cavity of higher temperature and entropy but with lower pressure.<\/p>\n According to the paper, the diffuse emission in Abell 3558 exhibits a mini-halo-like structure confined by cold fronts in the core, likely powered by turbulence from gas sloshing. Moreover, it showcases a ridge-like structure extending along the cluster axis aligned with a low-entropy gas trail, which may be powered by larger-scale sloshing turbulence.<\/p>\n Therefore, based on the obtained results, the astronomers concluded that the observed diffuse radio emission is a radio mini-halo.<\/p>\n In general, radio mini-halos are found mainly in dynamically relaxed systems hosting cool-cores, where no major merger event has occurred. Although their origin is still uncertain, it is assumed that they are powered by turbulent re-acceleration induced by gas sloshing and\/or active galactic nucleus<\/a> (AGN) feedback processes.<\/p>\n \n Written for you by our author Tomasz Nowakowski<\/a>, More information: \n\t\t\t\t\t\t\t\t\t\t\t\t\tJournal information: \t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/p>\n \n\t\t\t\t\t\t\t\t\t\t\t\t \u00a9 2025 Science X Network\n\t\t\t\t\t\t\t\t\t\t\t <\/p>\n \n\t\t\t\t\t\t\t\t\t\t\t\tCitation: \n\t\t\t\t\t\t\t\t\t\t\t This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
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\n\t\t\t\t\t\t\t\t\t\t\t\tK. S. Trehaeven et al, The Peculiar Mini-Halo in the Shapley Supercluster Member Abell 3558, arXiv (2025). DOI: 10.48550\/arxiv.2507.07549<\/a><\/p>\n
\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tarXiv<\/a>
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\n\t\t\t\t\t\t\t\t\t\t\t\tGalaxy cluster Abell 3558 has a peculiar mini-halo, observations suggest (2025, July 17)
\n\t\t\t\t\t\t\t\t\t\t\t\tretrieved 17 July 2025
\n\t\t\t\t\t\t\t\t\t\t\t\tfrom https:\/\/phys.org\/news\/2025-07-galaxy-cluster-abell-peculiar-mini.html\n\t\t\t\t\t\t\t\t\t\t\t <\/p>\n
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