相关论文: Diffuse Cluster-wide Radio Halos
About 1/3 of X-ray-luminous clusters show smooth, unpolarized radio emission on ~Mpc scales, known as giant radio halos. One promising model for radio halos is Fermi-II acceleration of seed relativistic electrons by turbulence of the…
In some clusters of galaxies, a diffuse non-thermal emission is present, not obviously associated with any individual galaxy. These sources have been identified as relics, mini-halos, and halos according to their properties and position…
Radio halos are diffuse synchrotron sources on scales of ~1 Mpc that are found in merging clusters of galaxies, and are believed to be powered by electrons re-accelerated by the merger-driven turbulence. We present measurements of extended…
The knowledge of the origin and statistical properties of diffuse radio emission in galaxy clusters has appreciably improved thanks to the GMRT Radio Halo Survey, a project based on 610 MHz observations of clusters belonging to a…
Some galaxy clusters show diffuse radio emission in the form of giant halos (GHs) on Mpc scales or minihalos (MHs) on smaller scales. Comparing VLA and XMM radial profiles of several such clusters, we find a universal linear correlation…
A brief overview on the theory and observations of relativistic particle populations in clusters of galaxies is given. The following topics are addressed: (i) the diffuse relativistic electron population within the intra-cluster medium…
We present here new images of relics and halo sources in rich cluster of galaxies and the correlation between the halo radio surface brightness versus the cluster bolometric X-ray luminosity.
Many galaxy clusters host Megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the power of radio halos and the thermal properties of the hosting clusters were…
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…
Giant radio halos are the most relevant examples of diffuse synchrotron emission from galaxy clusters. A number of these sources have very steep spectrum, with spectral index $\alpha \geq 1.5-1.6$ ($F(\nu) \propto \nu^{-\alpha}$), and are…
As energetic particles diffuse out of radio and star-forming galaxies (SFGs), their intracluster density builds up to a level that could account for a substantial part or all the emission from a radio halo. We calculate the particle…
We combine all available information about the spectral shape and morphology of the radio halo of the Coma cluster with the gamma-ray upper limits obtained by the Fermi-LAT and with the magnetic field strength derived from Faraday rotation…
Radio halos and radio relics are diffuse synchrotron sources that extend over Mpc-scales and are found in a number of merger galaxy clusters. They are believed to form as a consequence of the energy that is dissipated by turbulence and…
Radio observations over the last two decades have provided evidence that diffuse synchrotron emission in the form of megaparsec-scale radio halos in galaxy clusters is likely tracing regions of the intracluster medium where relativistic…
We assume that the supersymmetric lightest neutralino is a good candidate for the CDM and explore the possibility to produce diffuse radio emission from high-energy electrons arising from the neutralino annihilation in galaxy clusters whose…
Here we present Halo-FDCA, a robust open source Python package for modeling and estimating total flux densities of radio (mini) halos in galaxy clusters. Radio halos are extended ( ~200 - 1500 kpc in size) synchrotron emitting sources found…
We developed a magneto-turbulent model for the cosmic ray (CR) electrons seen in the radio halo clusters of galaxies. Steady state momentum distribution functions of the CR electrons are calculated for given spectra of the turbulent Alfven…
The first detection of a diffuse radio source in a cluster of galaxies, dates back to the 1959 (Coma Cluster, Large et al. 1959). Since then, synchrotron radiating radio sources have been found in several clusters, and represent an…
Giant radio halos (RH) are Mpc-scale synchrotron sources detected in a significant fraction of massive and merging galaxy clusters.Their statistical properties can be used to discriminate among various models for their origin. Theoretical…
We present new, high frequency radio observations of the merging galaxy clusters PLCK G287.0+32.9, Abell 2744, and Bullet. These clusters are known to host $\sim$Mpc scale sources, known as radio halos, which are formed by the acceleration…