Issue |
A&A
Volume 666, October 2022
|
|
---|---|---|
Article Number | A8 | |
Number of page(s) | 23 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361/202244179 | |
Published online | 27 September 2022 |
Using the polarization properties of double radio relics to probe the turbulent compression scenario⋆
1
Dipartimento di Fisica e Astronomia, Università di Bologna, via Gobetti 93/2, 40129 Bologna, Italy
e-mail: chiara.stuardi2@unibo.it
2
INAF – Istituto di Radioastronomia di Bologna, Via Gobetti 101, 40129 Bologna, Italy
3
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
4
Leiden Observatory, Leiden University, PO Box 9513 2300 RA Leiden, The Netherlands
Received:
3
June
2022
Accepted:
1
July
2022
Context. Radio relics are megaparsec-sized synchrotron sources located in the outskirts of some merging galaxy clusters. Binary-merging systems with a favorable orientation may host two almost symmetric relics, named double radio relics.
Aims. Double radio relics are seen preferentially edge-on and, thus, constitute a privileged sample for statistical studies. Their polarization and Faraday rotation properties give direct access to the relics’ origin and magnetic fields.
Methods. In this paper, we present a polarization and rotation measure (RM) synthesis study of four clusters hosting double radio relics, namely 8C 0212+703, Abell 3365, and PLCK G287.0+32.9; previously missing polarization studies; and ZwCl 2341+0000, for which conflicting results have been reported. We used 1–2 GHz Karl G. Jansky Very Large Array observations. We also provide an updated compilation of known double radio relics with important observed quantities. We studied their polarization and Faraday rotation properties at 1.4 GHz and we searched for correlations between fractional polarization and physical resolution, the distance from the cluster center, and the shock Mach number.
Results. The weak correlations found between these quantities are well reproduced by state-of-the-art magneto-hydrodynamical simulations of radio relics, confirming that merger shock waves propagate in a turbulent medium with tangled magnetic fields. Both external and internal Faraday depolarization should play a fundamental role in determining the polarization properties of radio relics at 1.4 GHz. Although the number of double radio relics with RM information is still low, their Faraday rotation properties (i.e., rest-frame RM and RM dispersion below 40 rad m−2 and non-Gaussian RM distribution) can be explained in the scenario in which shock waves with Mach numbers larger than 2.5 propagate along the plane of the sky and compress the turbulent intra-cluster medium.
Key words: galaxies: clusters: individual: 8C 0212+703 / galaxies: clusters: individual: Abell 3365 / magnetic fields / galaxies: clusters: individual: PLCK G287.0+32.9 / galaxies: clusters: individual: ZwCl 2341+0000 / galaxies: clusters: intracluster medium
The reduced images are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr> (130.79.128.5>) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/666/A8
© C. Stuardi et al. 2022
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe-to-Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.