J/A+A/666/A8 The polarization of double radio relics (Stuardi+, 2022)
Using the polarization properties of double radio relics to probe the turbulent
compression scenari.
Stuardi C., Bonafede A., Rajpurohit K., Brueggen M., de Gasperin F.,
Hoang D., van Weeren R.J.. Vazza F.
<Astron. Astrophys. 666, A8 (2022)>
=2022A&A...666A...8S 2022A&A...666A...8S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Radio sources ; Polarization
Keywords: galaxies: clusters: individual: 8C 0212+703 -
galaxies: clusters: individual: Abell 3365 -
galaxies: clusters: individual: PLCK G287.0+32.9 -
galaxies: clusters: individual: ZwCl 2341+0000 -
galaxies: clusters: intracluster medium - magnetic fields
Abstract:
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.
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.
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 1-2GHz 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 1.4GHz and we
searched for correlations between fractional polarization and physical
resolution, distance from the cluster center, and shock Mach number.
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 1.4GHz.
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 40rad/m2 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.
Description:
The four clusters, 8C 0212+703, Abell 3365, PLCK G287.0+32.9 and ZwCl
2341+0000, have been observed with the JVLA in the Lband (1-2GHz)
within the observing proposal 17A-083.
We used C- and D-configuration observations. 8C 0212+703 and Abell 3365
were observed with two separated pointings on the two relics to
maximize the sensitivity in the region of interest.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 152 12 List of fits images
fits/* . 12 Individual fits images
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 48 A21 "datime" Obs.date Observation date
50- 55 F6.4 GHz Freq ? Observed frequency
57- 60 I4 Kibyte size Size of FITS file
62-107 A46 --- FileName Name of FITS file, in subdirectory fits
109-152 A44 --- Title Title of the FITS file
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Acknowledgements:
Chiara Stuardi, ccstuardi(at)gmail.com
(End) Patricia Vannier [CDS] 20-Jul-2022