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dc.contributor.authorKnowles, K.
dc.contributor.authorIntema, Hubertus
dc.contributor.authorBaker, A.
dc.contributor.authorBharadwaj, V.
dc.contributor.authorBond, J.
dc.contributor.authorCress, C.
dc.contributor.authorGupta, N.
dc.contributor.authorHajian, A.
dc.contributor.authorHilton, M.
dc.contributor.authorHincks, A.
dc.contributor.authorHlozek, R.
dc.contributor.authorHughes, J.
dc.contributor.authorLindner, R.
dc.contributor.authorMarriage, T.
dc.contributor.authorMenanteau, F.
dc.contributor.authorMoodley, K.
dc.contributor.authorNiemack, M.
dc.contributor.authorReese, E.
dc.contributor.authorSievers, J.
dc.contributor.authorSifón, C.
dc.contributor.authorSrianand, R.
dc.contributor.authorWollack, E.
dc.identifier.citationKnowles, K. and Intema, H. and Baker, A. and Bharadwaj, V. and Bond, J. and Cress, C. and Gupta, N. et al. 2016. A giant radio halo in a low-mass SZ-selected galaxy cluster: ACT-CL J0256.5+0006. Monthly Notices of the Royal Astronomical Society. 459 (4): pp. 4240-4258.

We present the detection of a giant radio halo (GRH) in the Sunyaev-Zel'dovich (SZ)-selected merging galaxy cluster ACT-CL J0256.5+0006 (z = 0.363), observed with the Giant Metrewave Radio Telescope at 325 and 610 MHz. We find this cluster to host a faint (S610= 5.6 ± 1.4 mJy) radio halo with an angular extent of 2.6 arcmin, corresponding to 0.8 Mpc at the cluster redshift, qualifying it as a GRH. J0256 is one of the lowest mass systems, M500, SZ= (5.0 ± 1.2) × 1014M?, found to host a GRH. We measure the GRH at lower significance at 325 MHz (S325= 10.3 ± 5.3 mJy), obtaining a spectral index measurement of a325610= 1.0-0.9+0.7. This result is consistent with the mean spectral index of the population of typical radio haloes, a = 1.2 ± 0.2. Adopting the latter value, we determine a 1.4 GHz radio power of P1.4 GHz= (1.0 ± 0.3) × 1024W Hz-1, placing this cluster within the scatter of known scaling relations. Various lines of evidence, including the intracluster medium morphology, suggest that ACT-CL J0256.5+0006 is composed of two subclusters. We determine a merger mass ratio of 7:4, and a line-of-sight velocity difference of v? = 1880 ± 210 km s-1. We construct a simple merger model to infer relevant time-scales in the merger. From its location on the P1.4 GHz-LXscaling relation, we infer that we observe ACT-CL J0256.5+0006 just before first core crossing.

dc.publisherOxford University Press
dc.titleA giant radio halo in a low-mass SZ-selected galaxy cluster: ACT-CL J0256.5+0006
dc.typeJournal Article
dcterms.source.titleMonthly Notices of the Royal Astronomical Society

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

curtin.accessStatusOpen access

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