A New Enigmatic Radio Relic in the Low-mass Cluster Abell 2108

Document Type

Article

Publication Title

Monthly Notices of the Royal Astronomical Society

Abstract

We report the disco v ery ofã radio relic in the north-eastern periphery of the galaxy cluster Abell 2108 (A2108). A2108 is part of the uGMRT LOw-MAss Galaxy Cluster Surv e y (GLOMACS), where our mainãim is to search for diffuse radio emission signatures in very sparsely explored low-mass galaxy clusters using uGMRT band-3 (central frequency 400 MHz). We used our uGMRT band-3 observationsãlong with the existingãrchival band-3 uGMRT data to impro v e image sensitivity. Along with the previously reported south-western relic, the disco v ery of the new relic makes A2108 one of the few low-mass clusters hostingã double relic. The new relic spans o v erã re gion of 610 kpc ×310 kpcãnd, interestingly, differs considerably in sizeãnd morphology from the other relic. Using XMM-Newton scienceãrchive data, weãlso report the tentative detection ofã mildly supersonic shock of Mach number M SB = 1 . 42ãnd M T = 1 . 43 from the surface brightnessãnd temperature discontinuities, respecti vely, near this ne wly found relic. Both the relics in A2108ãre found to be significantly under-luminous compared with other double-relic systems in the mass-luminosity plane. Moreo v er, the north-eastern relic is remarkably under-luminous in the size-luminosity plane. Although mild supersonic shocks resulting fromãn off-axis merger could have influenced the origin of both relics, we hypothesize that local environments have playedã crucial role in shaping their morphologies.

First Page

10986

Last Page

10992

DOI

10.1093/mnras/stad3865

Publication Date

2-1-2024

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