On the Polarisation of Radio Relics

Hoeft, M.; Rajpurohit, K.; Wittor, Denis; Gennaro, G. Di; Domínguez-Fernández, Paola

doi:10.48550/arxiv.2201.03208

Cited by 2 publications

(7 citation statements)

References 17 publications

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“…A much smoother increase is expected for Mach numbers higher than 3, with < p >= 64 % for M = 4.5. A similar trend is obtained by more complex semi-analytical models which also considered the dependence on magnetic field strength (Hoeft et al 2022).…”

Section: Fractional Polarization and Mach Numbersupporting

confidence: 82%

“…This trend can be reproduced by simulations considering a M = 3 shock wave propagating through a medium perturbed by decaying subsonic turbulence in the ICM (Domínguez-Fernández et al 2021). This trend can be also reproduced with semi-analytical models based on shock compression of a small-scale tangled magnetic field, although this result was found to strongly depend on the magnetic field strength (Hoeft et al 2022). Furthermore, the morphology of simulated polarized emission resembles the structures of the underlying turbulent ICM, creating threads and filaments (Domínguez-Fernández et al 2021).…”

Section: Fractional Polarization and Depolarization Effectsmentioning

confidence: 64%

“…Furthermore, while the majority of injection-derived Mach numbers are lower than 3, the distribution of M int is shifted toward higher values where we expect a weaker correlation between fractional polarization and Mach number (see Fig. 1 in Hoeft et al 2022). If the Mach number distribution would be the one described by M inj we would have found a stronger correla-tion.…”

Section: Fractional Polarization and Mach Numbermentioning

confidence: 68%

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Using the polarization properties of double radio relics to probe the turbulent compression scenario

Stuardi

Bonafede

Rajpurohit

et al. 2022

A&A

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Context. Radio relics are megaparsec-sized synchrotron sources located in the outskirts of some merging galaxy clusters. Binarymerging 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., restframe 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.

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Section: Fractional Polarization and Mach Numbersupporting

confidence: 82%

Section: Fractional Polarization and Depolarization Effectsmentioning

confidence: 64%

Section: Fractional Polarization and Mach Numbermentioning

confidence: 68%

See 1 more Smart Citation

Using the polarization properties of double radio relics to probe the turbulent compression scenario

Stuardi

Bonafede

Rajpurohit

et al. 2022

A&A

View full text Add to dashboard Cite

show abstract

“…Furthermore, while the majority of injection-derived Mach numbers are lower than 3, the distribution of M int is shifted towards higher values where we expect a weaker correlation between fractional polarization and Mach number (see Fig. 1 in Hoeft et al 2022). If the Mach number distribution would be the one described by M inj we would have found a stronger correlation.…”

Section: Fractional Polarization and Mach Numbermentioning

confidence: 68%

“…-We found a weak positive correlation between the fractional polarization of relics and shock Mach number estimated from the integrated spectrum of radio relics (Spearman coefficient ∼ 0.3). Such a weak correlation is expected for Mach numbers higher than 2.5, while for lower values a stronger correlation would be expected (Hoeft et al 2022). This suggests that most radio relics reach a maximum Mach number higher than 2.5 and that Mach number estimates from X-ray or from injection radio spectral indexes are biased towards lower values.…”

Section: Discussionmentioning

confidence: 94%

Using the polarization properties of double radio relics to probe the turbulent compression scenario

Stuardi,

Bonafede,

Rajpurohit

et al. 2022

Preprint

View full text Add to dashboard Cite

Context. Radio relics are Mpc-size synchrotron sources located in the outskirts of some merging galaxy clusters. Binary-merging systems with 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, 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, distance from the cluster center, and 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., restframe 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.

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On the Polarisation of Radio Relics

Abstract: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Cited by 2 publications

References 17 publications

Using the polarization properties of double radio relics to probe the turbulent compression scenario

Using the polarization properties of double radio relics to probe the turbulent compression scenario

Using the polarization properties of double radio relics to probe the turbulent compression scenario

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