相关论文: Heating and Acceleration of Intracluster Medium El…
Recent observations of excess radiation at extreme ultraviolet and hard X-ray energies straddling the well known thermal soft X-ray emission have provided new tools and puzzles for investigation of the acceleration of nonthermal particles…
We investigate heating and acceleration of protons from a thermal gas with a generic diffusion and acceleration model, and subject to Coulomb scattering and energy loss, as was carried out in Petrosian & East (2008) for electrons. As…
We calculate the distribution of electrons in clusters of galaxies, resulting from thermalization processes in the presence of stochastic acceleration due to plasma waves. We show that the electron distribution can deviate from a…
We review the possible mechanisms for production of non-thermal electrons which are responsible for non-thermal radiation in clusters of galaxies. Our primary focus is on non-thermal Bremsstrahlung and inverse Compton scattering, that…
Evidence for nonthermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons, and new windows (in EUV and Hard X-ray ranges) have provided more powerful tools for its…
In this paper we review the possible radiation mechanisms for the observed non-thermal emission in clusters of galaxies, with a primary focus on the radio and hard X-ray emission. We show that the difficulty with the non-thermal,…
Some clusters of galaxies in addition to thermal bremsstrahlung (TB), emit diffuse radiation from the intercluster medium (ICM) at radio, EUV and hard x-ray (HXR) ranges. The radio radiation is due to synchrotron by relativistic electrons,…
We have developed a numerical model for the temporal evolution of particle and photon spectra resulting from nonthermal processes at the shock fronts formed in merging clusters of galaxies. Fermi acceleration is approximated by injecting…
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…
Nonthermal radiation is observed from clusters of galaxies in the radio, hard X-rays, and possibly in the soft X-ray/UV bands. While it is known that radiative processes related to nonthermal electrons are responsible for this radiation,…
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…
We consider nonthermal emission from clusters of galaxies produced by particle acceleration by resonant scattering of Alfv\'{e}n waves driven by fluid turbulence through the Lighthill mechanism in the intracluster medium. We assume that the…
We consider electron acceleration by obliquely propagating fast mode waves in magnetically dominated accretion disk coronae. For low coronal plasma densities, acceleration can exceed Coulomb drag at lower energies and energize electrons out…
The origin of hard X-ray (HXR) excess emission from clusters of galaxies is still an enigma, whose nature is debated. One of the possible mechanism to produce this emission is the bremsstrahlung model. However, previous analytical and…
We have developed a numerical model for the temporal evolution of particle and photon spectra resulting from nonthermal processes at the shock fronts formed in merging clusters of galaxies. Fermi acceleration is approximated by injecting…
Subcluster interactions within clusters of galaxies produce shocks that accelerate nonthermal particles. We treat Fermi acceleration of nonthermal electrons and protons by injecting power-law distributions of particles during the merger…
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 have investigated evolution of non-thermal emission from relativistic electrons accelerated at around the shock fronts during merger of clusters of galaxies. We estimate synchrotron radio emission and inverse Compton scattering of cosmic…
We have calculated nonthermal bremsstrahlung (NTB) models for the hard X-ray (HXR) tails recently observed by BeppoSAX in clusters of galaxies. In these models, the HXR emission is due to suprathermal electrons with energies of about 10-200…
Thermal X-ray spectra of clusters of galaxies and other sources are commonly calculated assuming Maxwellian electron distributions. There are situations where this approximation is not valid, for instance near interfaces of hot and cold gas…