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arXiv · 2311.09287

Probing diffuse radio emission in bridges between galaxy clusters with uGMRT

G. V. Pignataro·A. Bonafede·G. Bernardi·C. J. Riseley·D. Dallacasa·T. Venturi
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Abstract

The main purpose of this work is to investigate the properties of the non-thermal emission in the interacting clusters pairs Abell 0399-Abell 0401 and Abell 21-PSZ2 G114.9, found in an interacting state. In both cases their connection along a filament is supported by SZ effect detected by the Planck satellite and, in the special case of Abell 0399-Abell 0401, the presence of a radio bridge has been already confirmed by LOFAR observations at 140MHz. Here, we analyse new high sensitivity wideband (250-500MHz) uGMRT data of these two systems and describe an injection procedure to place limits on the spectrum of Abell 0399-Abell 0401 and on the radio emission between Abell 21-PSZ2 G114.9. For the A399-A401 pair, we are able to constrain the steep spectral index of the bridge emission to be alpha>2.2 with a 95% confidence level between 140MHz and 400MHz. For the A21-PSZ2 G114.9 pair, we are able to place an upper limit on the flux density of the bridge emission with two different methods, finding at the central frequency of 383MHz a conservative value of fu_1<260mJy at 95% confidence level, and a lower value of fu_2<125mJy at 80% confidence level, based on visual inspection and a morphological criterion. Our work provides a constraint on the spectrum in the bridge A399-A401 which disfavours shock-acceleration as the main mechanism for the radio emission.

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G. V. Pignataro, A. Bonafede, G. Bernardi, C. J. Riseley, D. Dallacasa, T. Venturi. 2023-11-15. Probing diffuse radio emission in bridges between galaxy clusters with uGMRT. https://arxiv.org/abs/2311.09287

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