A uGMRT and MeerKAT Study of Radio Relics in the Low-mass Merging Cluster PSZ2 G200.95−28.16
Diffuse radio sources known as radio relics are direct tracers of shocks in the outskirts of merging galaxy clusters. PSZ2 G200.95–28.16, a low-mass merging cluster ( M _500 = (2.7 ± 0.2) × 10 ^14 M _⊙ ), features a prominent radio relic, first identified by R. Kale et al. We name this relic as the...
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2025-01-01
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| author | Arpan Pal Ruta Kale Qian H. S. Wang Daniel R. Wik |
| author_facet | Arpan Pal Ruta Kale Qian H. S. Wang Daniel R. Wik |
| author_sort | Arpan Pal |
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| description | Diffuse radio sources known as radio relics are direct tracers of shocks in the outskirts of merging galaxy clusters. PSZ2 G200.95–28.16, a low-mass merging cluster ( M _500 = (2.7 ± 0.2) × 10 ^14 M _⊙ ), features a prominent radio relic, first identified by R. Kale et al. We name this relic as the Seahorse. The MeerKAT Galaxy Cluster Legacy Survey has confirmed two additional radio relics, R2 and R3, in this cluster. We present new observations of this cluster with the upgraded Giant Metrewave Radio Telescope (uGMRT) at 400 and 650 MHz, paired with Chandra X-ray data. The largest linear sizes for the three relics are 1.53 Mpc, 1.12 kpc, and 340 kpc. All three radio relics are polarized at 1283 MHz. Assuming the diffusive shock acceleration model, the spectral indices of the relics imply shock Mach Numbers of 3.1 ± 0.8 and 2.8 ± 0.9 for the Seahorse and R2, respectively. The Chandra X-ray surface brightness map shows two prominent subclusters, but the relics are not perpendicular to the likely merger axis, as typically observed; no shocks are detected at the locations of the relics. We discuss possible merger scenarios in light of the low mass of the cluster and the radio and X-ray properties of the relics. The relic R2 follows the correlation known in the radio relic power and cluster-mass plane, but the Seahorse and R3 relics are outliers. We have also discovered a radio ring in our 650 MHz uGMRT image that could be an Odd Radio Circle candidate. |
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| spelling | doaj-art-0597e5836e0c45679b948ce7e64b383d2025-08-20T03:17:18ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-019791410.3847/1538-4357/ad9903A uGMRT and MeerKAT Study of Radio Relics in the Low-mass Merging Cluster PSZ2 G200.95−28.16Arpan Pal0https://orcid.org/0009-0007-8409-4233Ruta Kale1https://orcid.org/0000-0003-1449-3718Qian H. S. Wang2https://orcid.org/0000-0001-8468-9164Daniel R. Wik3https://orcid.org/0000-0001-9110-2245National Centre for Radio Astrophysics, Tata Institute of Fundamental Research , S. P. Pune University Campus, Ganeshkhind, Pune 411007, IndiaNational Centre for Radio Astrophysics, Tata Institute of Fundamental Research , S. P. Pune University Campus, Ganeshkhind, Pune 411007, IndiaDepartment of Physics & Astronomy, The University of Utah , 115 South 1400 East, Salt Lake City, UT 84112, USADepartment of Physics & Astronomy, The University of Utah , 115 South 1400 East, Salt Lake City, UT 84112, USADiffuse radio sources known as radio relics are direct tracers of shocks in the outskirts of merging galaxy clusters. PSZ2 G200.95–28.16, a low-mass merging cluster ( M _500 = (2.7 ± 0.2) × 10 ^14 M _⊙ ), features a prominent radio relic, first identified by R. Kale et al. We name this relic as the Seahorse. The MeerKAT Galaxy Cluster Legacy Survey has confirmed two additional radio relics, R2 and R3, in this cluster. We present new observations of this cluster with the upgraded Giant Metrewave Radio Telescope (uGMRT) at 400 and 650 MHz, paired with Chandra X-ray data. The largest linear sizes for the three relics are 1.53 Mpc, 1.12 kpc, and 340 kpc. All three radio relics are polarized at 1283 MHz. Assuming the diffusive shock acceleration model, the spectral indices of the relics imply shock Mach Numbers of 3.1 ± 0.8 and 2.8 ± 0.9 for the Seahorse and R2, respectively. The Chandra X-ray surface brightness map shows two prominent subclusters, but the relics are not perpendicular to the likely merger axis, as typically observed; no shocks are detected at the locations of the relics. We discuss possible merger scenarios in light of the low mass of the cluster and the radio and X-ray properties of the relics. The relic R2 follows the correlation known in the radio relic power and cluster-mass plane, but the Seahorse and R3 relics are outliers. We have also discovered a radio ring in our 650 MHz uGMRT image that could be an Odd Radio Circle candidate.https://doi.org/10.3847/1538-4357/ad9903Galaxy clustersIntracluster mediumExtragalactic radio sourcesRadio continuum emission |
| spellingShingle | Arpan Pal Ruta Kale Qian H. S. Wang Daniel R. Wik A uGMRT and MeerKAT Study of Radio Relics in the Low-mass Merging Cluster PSZ2 G200.95−28.16 The Astrophysical Journal Galaxy clusters Intracluster medium Extragalactic radio sources Radio continuum emission |
| title | A uGMRT and MeerKAT Study of Radio Relics in the Low-mass Merging Cluster PSZ2 G200.95−28.16 |
| title_full | A uGMRT and MeerKAT Study of Radio Relics in the Low-mass Merging Cluster PSZ2 G200.95−28.16 |
| title_fullStr | A uGMRT and MeerKAT Study of Radio Relics in the Low-mass Merging Cluster PSZ2 G200.95−28.16 |
| title_full_unstemmed | A uGMRT and MeerKAT Study of Radio Relics in the Low-mass Merging Cluster PSZ2 G200.95−28.16 |
| title_short | A uGMRT and MeerKAT Study of Radio Relics in the Low-mass Merging Cluster PSZ2 G200.95−28.16 |
| title_sort | ugmrt and meerkat study of radio relics in the low mass merging cluster psz2 g200 95 28 16 |
| topic | Galaxy clusters Intracluster medium Extragalactic radio sources Radio continuum emission |
| url | https://doi.org/10.3847/1538-4357/ad9903 |
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