The Peculiar Mini-Halo in the Shapley Supercluster Member Abell 3558

Fuente: arXiv
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Autori principali: Trehaeven, K. S., Venturi, T., Smirnov, O., Di Gennaro, G., Rossetti, M., Giacintucci, S., Bardelli, S., Merluzzi, P., Sikhosana, S. P., Dallacasa, D., Kale, R., Knowles, K.
Natura: Preprint
Pubblicazione: 2025
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author Trehaeven, K. S.
Venturi, T.
Smirnov, O.
Di Gennaro, G.
Rossetti, M.
Giacintucci, S.
Bardelli, S.
Merluzzi, P.
Sikhosana, S. P.
Dallacasa, D.
Kale, R.
Knowles, K.
author_facet Trehaeven, K. S.
Venturi, T.
Smirnov, O.
Di Gennaro, G.
Rossetti, M.
Giacintucci, S.
Bardelli, S.
Merluzzi, P.
Sikhosana, S. P.
Dallacasa, D.
Kale, R.
Knowles, K.
contents We present a multi-band study of the diffuse emission in the galaxy cluster Abell 3558, located in the core of the Shapley Supercluster. Using new MeerKAT UHF-Band and uGMRT Band-3 observations, and published MeerKAT L-band and ASKAP 887 MHz data, we perform a detailed analysis of the diffuse emission in the cluster centre. We complement with XMM-Newton X-ray information for a thorough study of the connection between the thermal and non-thermal properties of the cluster. We find that the diffuse radio emission in the cluster centre is more extended than published earlier, with a previously undetected extension spanning 100 kpc towards the north beyond the innermost cold front, increasing the total size of the emission to 550 kpc, and shows a clear spatial correlation with the X-ray features. The overall radio spectrum is steep ($α_{\rm 400\,MHz}^{\rm 1569\,MHz}=1.18\pm0.10$), with local fluctuations which show several connections with the X-ray surface brightness, cold fronts, and residual emission. The point-to-point correlation between the radio and X-ray surface brightness is sub-linear, and steepens with increasing frequency. We discuss the classification of the diffuse emission considering its overall properties, those of the ICM, and the existing scaling laws between the radio and X-ray quantities in galaxy clusters. We conclude that it is a mini-halo, powered by turbulent (re)-acceleration induced by sloshing motions within the cluster region delimited by the cold fronts, and it supports the picture of a known minor merger between A\,3558 and the group SC\,1327--312 with mass ratio 5:1.
format Preprint
id arxiv_https___arxiv_org_abs_2507_07549
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Peculiar Mini-Halo in the Shapley Supercluster Member Abell 3558
Trehaeven, K. S.
Venturi, T.
Smirnov, O.
Di Gennaro, G.
Rossetti, M.
Giacintucci, S.
Bardelli, S.
Merluzzi, P.
Sikhosana, S. P.
Dallacasa, D.
Kale, R.
Knowles, K.
Astrophysics of Galaxies
We present a multi-band study of the diffuse emission in the galaxy cluster Abell 3558, located in the core of the Shapley Supercluster. Using new MeerKAT UHF-Band and uGMRT Band-3 observations, and published MeerKAT L-band and ASKAP 887 MHz data, we perform a detailed analysis of the diffuse emission in the cluster centre. We complement with XMM-Newton X-ray information for a thorough study of the connection between the thermal and non-thermal properties of the cluster. We find that the diffuse radio emission in the cluster centre is more extended than published earlier, with a previously undetected extension spanning 100 kpc towards the north beyond the innermost cold front, increasing the total size of the emission to 550 kpc, and shows a clear spatial correlation with the X-ray features. The overall radio spectrum is steep ($α_{\rm 400\,MHz}^{\rm 1569\,MHz}=1.18\pm0.10$), with local fluctuations which show several connections with the X-ray surface brightness, cold fronts, and residual emission. The point-to-point correlation between the radio and X-ray surface brightness is sub-linear, and steepens with increasing frequency. We discuss the classification of the diffuse emission considering its overall properties, those of the ICM, and the existing scaling laws between the radio and X-ray quantities in galaxy clusters. We conclude that it is a mini-halo, powered by turbulent (re)-acceleration induced by sloshing motions within the cluster region delimited by the cold fronts, and it supports the picture of a known minor merger between A\,3558 and the group SC\,1327--312 with mass ratio 5:1.
title The Peculiar Mini-Halo in the Shapley Supercluster Member Abell 3558
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2507.07549