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EnglishRadio relics are elongated sources related to shocks driven by galaxy cluster merger events. Although these objects are highly polarized at GHz frequencies (greater than or similar to 20%), high-resolution studies of their polarization properties are still lacking. We present the first high-resolution and high-sensitivity polarimetry study of the merging galaxy cluster CIZA J2242.8+5301 in the 1-4 GHz frequency band. We use the QU-fitting approach to model the Stokes I, Q, and U emission, obtaining best-fit intrinsic polarization fraction (p(0)), intrinsic polarization angle (chi(0)), rotation measure (RM), and wavelength-dependent depolarization (sigma(RM)) maps of the cluster. Our analysis focuses on the northern relic (RN). For the first time in a radio relic, we observe a decreasing polarization fraction in the downstream region. Our findings are possibly explained by geometrical projections and/or by decreasing of the magnetic field anisotropy toward the cluster center. From the amount of depolarization of the only detected background radio galaxy, we estimate a turbulent magnetic field strength of B-turb similar to 5.6 mu G in the relic. Finally, we observe RM fluctuations of about 30 rad m(-2) around the median value of 140.8 rad m(-2) at the relic position.
| Titolo: | Downstream Depolarization in the Sausage Relic: A 1–4 GHz Very Large Array Study | |
| Autore/i: | Di Gennaro, G.; van Weeren, R. J.; Rudnick, L.; Hoeft, M.; Brüggen, M.; Ryu, Dongsu; Röttgering, H. J. A.; Forman, W.; Stroe, A.; Shimwell, T. W.; Kraft, R. P.; Jones, C.; Hoang, D. N. | |
| Autore/i Unibo: | ||
| Anno: | 2021 | |
| Rivista: | ||
| Digital Object Identifier (DOI): | http://dx.doi.org/10.3847/1538-4357/abe620 | |
| Abstract: | Radio relics are elongated sources related to shocks driven by galaxy cluster merger events. Although these objects are highly polarized at GHz frequencies (greater than or similar to 20%), high-resolution studies of their polarization properties are still lacking. We present the first high-resolution and high-sensitivity polarimetry study of the merging galaxy cluster CIZA J2242.8+5301 in the 1-4 GHz frequency band. We use the QU-fitting approach to model the Stokes I, Q, and U emission, obtaining best-fit intrinsic polarization fraction (p(0)), intrinsic polarization angle (chi(0)), rotation measure (RM), and wavelength-dependent depolarization (sigma(RM)) maps of the cluster. Our analysis focuses on the northern relic (RN). For the first time in a radio relic, we observe a decreasing polarization fraction in the downstream region. Our findings are possibly explained by geometrical projections and/or by decreasing of the magnetic field anisotropy toward the cluster center. From the amount of depolarization of the only detected background radio galaxy, we estimate a turbulent magnetic field strength of B-turb similar to 5.6 mu G in the relic. Finally, we observe RM fluctuations of about 30 rad m(-2) around the median value of 140.8 rad m(-2) at the relic position. | |
| Data stato definitivo: | 2021-04-21T10:23:39Z | |
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