Related papers: Shock acceleration efficiency in radio relics
The number of diffuse radio halos in clusters of galaxies has grown in recent years, making it possible to derive statistical properties of these sources and of the hosting clusters. We show that diffuse sources are associated with X-ray…
Giant radio relics in the outskirts of galaxy clusters are known to be lit up by the relativistic electrons produced via diffusive shock acceleration (DSA) in shocks with low sonic Mach numbers, $M_{\rm s}\lesssim3$. The particle…
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…
Radio relics are the manifestation of electrons presumably being shock (re-)accelerated to high energies in the outskirts of galaxy clusters. However, estimates of the shocks' strength yield different results when measured with radio or…
We describe multiwavelength optical, X-ray and radio evidences of energetic mergers in southern galaxy cluster Abell 3376 (A3376, redshift z=0.046, X-ray luminosity $ \rm L_{X}(0.1-2.4 keV)= 2.48 \times 10^{44} erg s^{-1}$). Here we report…
Radio emissions from young supernovae (~ 1 year after the explosion) show a peculiar feature in the relativistic electron population at a shock wave, where their energy distribution is steeper than typically found in supernova remnants…
Cosmological hydrodynamic simulations have demonstrated that shock waves could be produced in the intergalactic medium by supersonic flow motions during the course of hierarchical clustering of the large-scale-structure in the Universe.…
Both, X-ray and radio observations, are beginning to probe regions in galaxy clusters close to the virial radius. These are particularly interesting regions as they are (i) crucial for the thermal evolution of the intra-cluster medium and…
In order for diffusive shock acceleration (DSA) to accelerate particles to high energies, the energetic particles must be able to interact with magnetic turbulence over a broad wavelength range. The weakly anisotropic distribution of…
Recent observations have revealed detailed structures of radio relics in a wide range of frequencies. In this work, we perform three-dimensional magnetohydrodynamical simulations of merger shocks propagating through a turbulent magnetized…
We present here results from observations at 5.5 and 9 GHz of the Bullet cluster 1E 0657-55.8 with the Australia Telescope Compact Array (ATCA). Our results show detection of diffuse emission in the cluster. Our findings are consistent with…
Radio halos are synchrotron diffuse sources at the centre of a fraction of galaxy clusters. The study of large samples of clusters with adequate radio and X-ray data is necessary to investigate the origin of radio halos and their connection…
Cosmology models predict that external accretion shocks form in the outer region of galaxy clusters due to supersonic gas infall from filaments and voids in the cosmic web. They are characterized by high sonic and Alfv\'enic Mach numbers,…
We search for extended regions of radio emission not associated with Active Galactic Nuclei, known as 'relics', 'halos' and 'mini halo's, in a sample of 70 Abell clusters for which we have radio, optical and X-ray data. AGN can produce…
Radio relics in galaxy clusters are believed to trace merger shock fronts. If cosmological structure formation determines the luminosity, size and shape distributions of radio relics then merger shocks need to be lighted up in a homogeneous…
The existence and extent of non-thermal phenomena in galaxy clusters is now well established. A key question in our understanding of these phenomena is the origin of the relativistic electrons which may be constrained by the modelling of…
Radio relics are diffuse, extended synchrotron sources located at the outskirts of merging galaxy clusters. Their origin has been linked with shock waves injected into the intracluster medium, but the acceleration mechanism at the shock…
We propose semi-analytic models for the electron momentum distribution in weak shocks that accounts for both in situ acceleration and re-acceleration through diffusive shock acceleration (DSA). In the former case, a small fraction of…
We investigate the acceleration of particles via the second-order Fermi process in the lobes of giant radio galaxies. Such sites are candidates for the accelerators of ultra-high energy cosmic rays. We focus on the nearby FR I radio galaxy…
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…