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Radio fossils, relics, and haloes in Abell 3266: cluster archaeology with ASKAP-EMU and the ATCA

Abstract : Abell 3266 is a massive and complex merging galaxy cluster that exhibits significant substructure. We present new, highly sensitive radio continuum observations of Abell 3266 performed with the Australian Square Kilometre Array Pathfinder (0.8-1.1 GHz) and the Australia Telescope Compact Array (1.1-3.1 GHz). These deep observations provide new insights into recently reported diffuse non-thermal phenomena associated with the intracluster medium, including a 'wrong-way' relic, a fossil plasma source, and an as-yet unclassified central diffuse ridge, which we reveal comprises the brightest part of a large-scale radio halo detected here for the first time. The 'wrong-way' relic is highly atypical of its kind: it exhibits many classical signatures of a shock-related radio relic, while at the same time exhibiting strong spectral steepening. While radio relics are generally consistent with a quasi-stationary shock scenario, the 'wrong-way' relic is not. We study the spectral properties of the fossil plasma source; it exhibits an ultrasteep and highly curved radio spectrum, indicating an extremely aged electron population. The larger scale radio halo fills much of the cluster centre, and presents a strong connection between the thermal and non-thermal components of the intracluster medium, along with evidence of substructure. Whether the central diffuse ridge is simply a brighter component of the halo, or a mini-halo, remains an open question. Finally, we study the morphological and spectral properties of the multiple complex radio galaxies in this cluster in unprecedented detail, tracing their evolutionary history.
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Contributor : Nathalie POTHIER Connect in order to contact the contributor
Submitted on : Friday, November 11, 2022 - 5:59:37 PM
Last modification on : Saturday, November 12, 2022 - 3:45:07 AM


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C. J. Riseley, E. Bonnassieux, T. Vernstrom, T. J. Galvin, A. Chokshi, et al.. Radio fossils, relics, and haloes in Abell 3266: cluster archaeology with ASKAP-EMU and the ATCA. Monthly Notices of the Royal Astronomical Society, 2022, 515, pp.1871-1896. ⟨10.1093/mnras/stac1771⟩. ⟨insu-03849376⟩



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