相关论文: Cosmic Rays and Non-Thermal Emission in Galaxy Clu…
A short review on theoretical implications of non-thermal emission (radio, extreme ultraviolet, high energy X-ray) from the intra-cluster medium is given. The origin of cluster radio halos and cluster radio relics is discussed within the…
The discovery of diffuse synchrotron radio emission and, more recently, of the hard X-ray (HXR) tails have triggered a growing interest about non-thermal phenomena in galaxy clusters. After a brief review of the most important evidences for…
Recent observations of high energy (> 20 keV) X-ray emission in a few clusters extend and broaden our knowledge of physical phenomena in the intracluster space. This emission is likely to be nonthermal, probably resulting from Compton…
We calculate the flux of radio, hard X-ray and UV radiation from clusters of galaxies as produced by synchrotron emission and Inverse Compton Scattering of electrons generated as secondaries in cosmic ray interactions in the intracluster…
Recent observations of high energy (> 20 keV) X-ray emission in a few clusters of galaxies broaden our knowledge of physical phenomena in the intracluster space. This emission is likely to be nonthermal, probably resulting from Compton…
We study non-thermal emissions from cool cores in galaxy clusters. We adopted a recent model, in which cosmic-rays (CRs) prevail in the cores and stably heat them through CR streaming. The non-thermal emissions come from the interaction…
Observations with the RXTE and SAX satellites have recently led to the measurement of a second component in the spectra of several clusters of galaxies which are known to have regions of extended radio emission. This new component is quite…
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…
I present a review of nonthermal processes in the large scale structure of the universe. After examining the properties of cosmological shock waves and their role as particle accelerators, I discuss the main observational facts, from radio…
There is compelling evidence that at least some clusters of galaxies are powerful sources of non-thermal radiation. In all cases where this radiation has been detected, a general trend is that high energy densities of cosmic rays and…
We address the role of gamma-ray astronomy in the investigation of nonthermal processes in the large scale structure of the universe. Based on EGRET upper limits on nearby galaxy clusters (GCs) we constrain the acceleration efficiency of CR…
Recent multifrequency observations contribute to derive a comprehensive picture of the origin and evolution of relativistic particles in galaxy clusters. In this review I briefly discuss theoretical aspects and open problems of this…
Multiwavelength observations suggest that clusters are reservoirs of vast amounts relativistic electrons and positrons that are either injected into and accelerated directly in the intra-cluster medium, or produced as secondary pairs by…
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…
FERMI (formely GLAST) will shortly provide crucial information on relativistic particles in galaxy clusters. We discuss non-thermal emission in the context of general calculations in which relativistic particles (protons and secondary…
Radio observations prove the existence of relativistic particles and magnetic field associated with the intra-cluster-medium (ICM) through the presence of extended synchrotron emission in the form of radio halos and peripheral relics. This…
Some clusters of galaxies have been identified as powerful sources of non-thermal radiation, from the radio to X-ray wavelengths. The classical models proposed for the explanation of this radiation usually require large energy densities in…
The existence of cosmic rays and weak magnetic fields in the intracluster volume has been well proven by deep radio observations of galaxy clusters. However a detailed physical characterization of the non-thermal component of large…
We calculate the fluxes of radio, hard X-rays and gamma-ray emission from clusters of galaxies, in the context of a secondary electron model (SEM). In the SEM the radiating electrons are produced by the decay of charged pions in cosmic ray…
FERMI (formely GLAST) and LOFAR will shortly provide crucial information on the non-thermal components (relativistic particles and magnetic field) in galaxy clusters. After discussing observational facts that already put constraints on the…