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

C. J. Riseley*, E. Bonnassieux, T. Vernstrom, T. J. Galvin, A. Chokshi, A. Botteon, K. Rajpurohit, S. W. Duchesne, A. Bonafede, L. Rudnick, M. Hoeft, B. Quici, D. Eckert, M. Brienza, C. Tasse, E. Carretti, J. D. Collier, J. M. Diego, L. Di Mascolo, A. M. HopkinsM. Johnston-Hollitt, R. R. Keel, B. S. Koribalski, T. H. Reiprich

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)
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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.

Original languageEnglish
Pages (from-to)1871-1896
Number of pages26
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - Sept 2022

Bibliographical note

Copyright the Author(s) 2022. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


  • galaxies: clusters: general
  • galaxies: clusters: individual: Abell 3266
  • galaxies: clusters: intracluster medium
  • X-rays: galaxies: clusters


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