The goal of this work is to investigate the Faraday rotation measure (RM) of radio galaxies in hot galaxy clusters in order to establish a possible connection between the magnetic field strength and the gas temperature of the intracluster medium. We performed Very Large Array observations at 3.6 cm and 6 cm of two radio galaxies located in A401 and Ophiuchus, a radio galaxy in A2142, and a radio galaxy located in the background of A2065. All these galaxy clusters are characterized by high temperatures. We obtained detailed RM images at an angular resolution of 3'' for most of the observed radio galaxies. The RM images are patchy and reveal fine substructures of a few kpc in size. Under the assumption that the radio galaxies themselves have no effect on the measured RMs, these structures indicate that the intracluster magnetic fields fluctuate down to such small scales. These new data are compared with RM information present in the literature for cooler galaxy clusters. For a fixed projected distance from the cluster center, clusters with higher temperature show a higher dispersion of the RM distributions (sigmaRM), mostly because of the higher gas density in these clusters. Although the previously known relation between the clusters X-ray surface brightness (Sx) at the radio galaxy location and sigmaRM is confirmed, a possible connection between the sigmaRM-Sx relation and the cluster temperature, if present, is very weak. Therefore, in view of the current data, it is impossible to establish a strict link between the magnetic field strength and the gas temperature of the intracluster medium.
Clusters of varying mass ratios can merge and the process significantly disturbs the cluster environments and alters their global properties. Active radio galaxies are another phenomenon that can also affect cluster environments. Radio jets can interact with the intra-cluster medium (ICM) and locally affect its properties. Abell~2384 (hereafter A2384) is a unique system that has a dense, hot X-ray filament or bridge connecting the two unequal mass clusters A2384(N) and A2384(S). The analysis of its morphology suggests that A2384 is a post-merger system where A2384(S) has already interacted wit…
Analysis of the correlation between the angular positions of distant radio galaxies on the sky and the orientations of their polarization vectors with respect to their major axes, indicates a dipolar anisotropy in the large scale. We consider a single mode of large-scale scalar perturbation to the FRW metric. Using Newman-Penrose formalism, we calculate the rotation of the galaxy major axis with respect to the polarization vector as the elliptic image and the polarization vector are carried through the perturbed space-time. The dependence of the rotation on the polar angular coordinate of the …
We introduce a new cross-correlation method to detect and verify the astrophysical origin of Faraday Rotation (FR) in multiwavelength surveys. FR is well studied in radio astronomy from radio point sources but the $λ^{2}$ suppression of FR makes detecting and accounting for this effect difficult at millimeter and sub-millimeter wavelengths. Therefore statistical methods are used to attempt to detect FR in the cosmic microwave background (CMB). Most estimators of the FR power spectrum rely on single frequency data. In contrast, we investigate the correlation of polarized CMB maps with FR measur…
