Related papers: Shock acceleration as origin of the radio relic in…
We observed three radio relics in galaxy clusters and one radio relic candidate at 4.85 and 8.35 GHz in total emission and linearly polarized emission with the Effelsberg 100-m telescope and one radio relic candidate in X-rays with the…
The origin of radio relics is usually explained via diffusive shock acceleration (DSA) or re-acceleration of electrons at/from merger shocks in galaxy clusters. The case of acceleration is challenged by the low predicted efficiency of…
The Toothbrush radio relic associated the merging cluster 1RXS J060303.3 is presumed to be produced by relativistic electrons accelerated at merger-driven shocks. Since the shock Mach number inferred from the observed radio spectral index,…
We present the discovery of a single radio relic located at the edge of the galaxy cluster A2384, using the MeerKAT radio telescope. A2384 is a nearby ($z$ = 0.092), low mass, complex bimodal, merging galaxy cluster that displays a dense…
Chandra observations of the merging galaxy cluster A520 reveal a prominent bow shock with M=2.1+0.4-0.3. This is only the second clear example of a substantially supersonic merger shock front in clusters. Comparison of the X-ray image with…
We report a discovery of a double radio relic in the cluster merger ZwCl1447.2+2619 ($z=0.376$) with uGMRT observations at $420\rm~MHz$ and $700\rm~MHz$. The linear sizes of the northern and southern relics are $\sim0.3~$Mpc and…
We present evidence for the existence of shock waves caused by the formation of the large-scale structure. In some clusters of galaxies peripherally located sources of extended diffuse radio emission exist, the so-called cluster radio…
We present an X-ray and radio study of the famous `El Gordo', a massive and distant ($z=0.87$) galaxy cluster. In the deep (340 ks) Chandra observation, the cluster appears with an elongated and cometary morphology, a sign of its current…
In Kang (2015) we calculated the acceleration of cosmic-ray electrons and the ensuing radio synchrotron emission at weak spherical shocks that are expected to form in the outskirts of galaxy clusters.There we demonstrated that, at…
We report the discovery of a putative radio relic, 830 kpc in length and found toward the outskirts of galaxy cluster Abell 1697 ($z=0.181$), using the LOFAR Two Meter Sky Survey (LoTSS) at 144 MHz. With an X-ray-inferred mass of…
Synchrotron radio emission is being detected from an increasing number of galaxy clusters. Spectral index images are a powerful tool to investigate the origin, nature, and connection of these sources with the dynamical state of the cluster.…
Radio relics are patches of diffuse synchrotron radio emission that trace shock waves. Relics are thought to form when intra-cluster medium electrons are accelerated by cluster merger induced shock waves through the diffusive shock…
We report on a Suzaku measurement of the shock feature associated with the western radio relic in the merging cluster A3376. The temperature profile is characterized by an almost flat radial shape with kT ~ 4 keV within 0.5 r200 and a rise…
We present the results of observations performed with the Sardinia Radio Telescope (SRT) at 1.3-1.8 GHz of the galaxy cluster CL 0217+70 and a $3^\circ \times 3^\circ$ region around it. We combine the SRT data with archival Very Large Array…
We present deep VLA observations of the merging galaxy cluster Abell 2256. This cluster is known to possess diffuse steep spectrum radio relic emission in the peripheral regions. Our new observations provide the first detailed image of the…
Galaxy clusters grow by a sequence of mergers with other clusters and galaxy groups. During these mergers, shocks and/or turbulence are created within the intracluster medium (ICM). In this process, particles could be accelerated to highly…
A number of radio observations have revealed the presence of large synchrotron-emitting sources associated with the intra-cluster medium. There is strong observational evidence that the emitting particles have been (re-)accelerated by…
Spectral index studies of halos, relics, and radio galaxies provide useful information on their origin and connection with merger processes. We present WSRT multi-wavelength observations of the galaxy cluster Abell 2255 at 25 cm, 85 cm, and…
We report the discovery of a radio halo in the massive merging cluster MACSJ2243.3-0935, as well as a new radio relic candidate, using the Giant Meterwave Radio Telescope and the KAT-7 telescope. The radio halo is coincident with the…
Low-frequency radio observations of galaxy clusters are the key to detecting the diffuse extended emission associated with them. The presence and properties of such radio sources in galaxy clusters reveal the existence of magnetic fields on…