2022A&A...657A...2R


Query : 2022A&A...657A...2R

2022A&A...657A...2R - Astronomy and Astrophysics, volume 657A, 2-2 (2022/1-1)

Turbulent magnetic fields in the merging galaxy cluster MACS J0717.5+3745.

RAJPUROHIT K., HOEFT M., WITTOR D., VAN WEEREN R.J., VAZZA F., RUDNICK L., RAJPUROHIT S., FORMAN W.R., RISELEY C.J., BRIENZA M., BONAFEDE A., RAJPUROHIT A.S., DOMINGUEZ-FERNANDEZ P., EILEK J., BONNASSIEUX E., BRUGGEN M., LOI F., ROTTGERING H.J.A., DRABENT A., LOCATELLI N., BOTTEON A., BRUNETTI G. and CLARKE T.E.

Abstract (from CDS):

We present wideband (1 - 6.5 GHz) polarimetric observations, obtained with the Karl G. Jansky Very Large Array, of the merging galaxy cluster MACS J0717.5+3745, which hosts one of the most complex known radio relic and halo systems. We used both rotation measure synthesis and QU-fitting to find a reasonable agreement of the results obtained with these methods, particularly when the Faraday distribution is simple and the depolarization is mild. The relic is highly polarized over its entire length (850 kpc), reaching a fractional polarization > 30% in some regions. We also observe a strong wavelength-dependent depolarization for some regions of the relic. The northern part of the relic shows a complex Faraday distribution, suggesting that this region is located in or behind the intracluster medium (ICM). Conversely, the southern part of the relic shows a rotation measure very close to the Galactic foreground, with a rather low Faraday dispersion, indicating very little magnetoionic material intervening along the line of sight. Based on a spatially resolved polarization analysis, we find that the scatter of Faraday depths is correlated with the depolarization, indicating that the tangled magnetic field in the ICM causes the depolarization. We conclude that the ICM magnetic field could be highly turbulent. At the position of a well known narrow-angle-tailed galaxy (NAT), we find evidence of two components that are clearly separated in the Faraday space. The high Faraday dispersion component seems to be associated with the NAT, suggesting the NAT is embedded in the ICM while the southern part of the relic lies in front of it. If true, this implies that the relic and this radio galaxy are not necessarily physically connected and, thus, the relic may, in fact, not be powered by the shock re-acceleration of fossil electrons from the NAT. The magnetic field orientation follows the relic structure indicating a well-ordered magnetic field. We also detected polarized emission in the halo region; however, the absence of significant Faraday rotation and a low value of Faraday dispersion suggests the polarized emission that was previously considered as the part of the halo does, in fact, originate from the shock(s).

Abstract Copyright: © ESO 2021

Journal keyword(s): galaxies: clusters: general - radiation mechanisms: non-thermal - polarization - acceleration of particles - magnetic fields - large-scale structure of Universe

VizieR on-line data: <Available at CDS (J/A+A/657/A2): list.dat fits/*>

CDS comments: Fig.1 Filaments F1 and F2 not in SIMBAD.

Simbad objects: 16

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Number of rows : 16
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 ACO 2744 ClG 00 14 20.03 -30 23 17.8           ~ 688 0
2 ACO 523 ClG 04 59 01 +08 46.5           ~ 48 0
3 ICRF J052109.8+163822 Sy1 05 21 09.88596258 +16 38 22.0515459   19.37 18.84 18.480   ~ 818 1
4 ICRF J054236.1+495107 Sy1 05 42 36.13789710 +49 51 07.2337139   18.45 17.80 17.210   ~ 1422 1
5 1RXS J060313.4+421231 X 06 03 13.40 +42 12 31.0           ~ 5 0
6 [VRB2009] R4 Rad 07 17 31.0 +37 44 45           ~ 1 0
7 [VRB2009] R3 Rad 07 17 33.0 +37 45 00           ~ 1 0
8 [VRB2009] R2 Rad 07 17 36.0 +37 45 30           ~ 1 0
9 ClG J0717+3745 ClG 07 17 36.50 +37 45 23.0           ~ 443 0
10 [VRB2009] R1 Rad 07 17 37.0 +37 46 15           ~ 1 0
11 NAME Coma Relic Rad 12 55 +27.2           ~ 56 0
12 BAX 199.3086-25.5133 ClG 13 14 31.5049 -25 15 56.602           ~ 98 0
13 ACO 2256 ClG 17 03 43.5 +78 43 03           ~ 865 1
14 ACO 2255 ClG 17 12 50.04 +64 03 10.6           ~ 546 0
15 ACO 2345 ClG 21 27 09.80 -12 09 58.8           ~ 126 1
16 NAME Sausage Cluster ClG 22 42 53.0 +53 01 05           ~ 192 0

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2023.01.30-21:45:10

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