Related papers: On the relation between mini-halos and AGN feedbac…
We present radio and X-ray studies of A3444 and MS1455.0+2232, two galaxy clusters with radio minihalos in their cool cores. A3444 is imaged using the Giant Metrewave Radio Telescope (GMRT) at 333, 607 and 1300 MHz and the Very Large Array…
AGN feedback is regarded as an important non-gravitational process in galaxy clusters, providing useful constraints on large-scale structure formation. It modifies the structure and energetics of the intra-cluster medium (ICM) and hence its…
Many relaxed cool-core clusters host diffuse radio emission on scales of hundreds of kiloparsecs: mini-haloes. However, the mechanism responsible for generating them, as well as their connection with central active galactic nuclei, is…
Active Galactic Nuclei (AGN) represent the growth phases of the supermassive black holes in the center of almost every galaxy. Powerful, highly ionized winds, with velocities $\sim 0.1- 0.2c$ are a common feature in X--ray spectra of…
Clusters of galaxies are turbulent environments, whether merging systems with a turbulent intracluster medium (ICM) or relaxed systems sloshing within the potential well. In many such clusters, diffuse radio sources associated with the ICM…
The Ophiuchus galaxy cluster exhibits a curious concave gas density discontinuity at the edge of its cool core. It was discovered in the Chandra X-ray image by Werner and collaborators, who considered a possibility of it being a boundary of…
Jet feedback from active galactic nuclei (AGN) harboured by brightest cluster galaxies is expected to play a fundamental role in regulating cooling in the intracluster medium (ICM). While observations and theory suggest energy within jet…
Active galactic nuclei (AGN) provide energetic feedback necessary to `turn off' star formation in high-mass galaxies (M$_{\rm halo} \geq $ 10$^{12.5}$ M$_{\odot}$, $10.4 \leq \log(\frac{M_*}{M_\odot}) \leq 11$) as observed. Cosmic rays…
Radio halos are extended and diffuse non-thermal radio sources present at the cluster center, not obviously associated with any individual galaxy. A strong correlation has been found between the cluster X-ray luminosity and the halo radio…
Radio mode feedback, in which most of the energy of an active galactic nucleus (AGN) is released in a kinetic form via radio-emitting jets, is thought to play an important role in the maintenance of massive galaxies in the present-day…
Galaxy clusters are located at the nodes of cosmic filaments and therefore host a lot of hydrodynamical activity. However, cool core clusters are considered to be relatively relaxed systems without much merging activity. The Abell 85…
Giant radio halos are Mpc-scale diffuse radio sources associated with the central regions of galaxy clusters. The most promising scenario to explain the origin of these sources is that of turbulent re-acceleration, in which MeV electrons…
Radio observations discovered large scale non thermal sources in the central Mpc regions of dynamically disturbed galaxy clusters (radio halos). The morphological and spectral properties of these sources suggest that the emitting electrons…
A long-standing problem for models of galaxy formation has been the mismatch between the predicted shape of the mass function of dark matter halos and the observed shape of the luminosity function of galaxies. The number of massive halos is…
We present VLA data at 330 MHz and 1.5 GHz of the radio emission observed in the cooling flow cluster A2626. By producing images at different resolutions we found that the radio source consists of different components: an unresolved core…
The most important evidence of non-thermal phenomena in galaxy clusters comes from Giant Radio Halos (GRHs), synchrotron radio sources extended over Mpc scales, detected in a growing number of massive galaxy clusters. A promising…
We have discovered new diffuse radio sources likely associated with groups of galaxies at low redshift (0.01-0.04) and without apparent AGN by using the WENSS and WISH catalogs to perform an unbiased survey. These sources resemble the radio…
The cores of massive galaxy clusters, where hot gas is cooling rapidly, appear to undergo cycles of self-regulating energy feedback, in which AGN outbursts in the central galaxies episodically provide sufficient heating to offset much of…
Previously it has been recognized that radio halos in galaxy clusters are preferentially associated with merging systems as indicated by substructure in the X-ray images and temperature maps. Since, however, many clusters without radio…
We show an interesting correlation between the surface brightness and temperature structure of the relaxed clusters RXJ1720.1+2638 and MS1455.0+2232, hosting a pair of cold fronts, and their central core--halo radio source. We discuss the…