Related papers: Nonthermal radiation mechanisms
We use 1+1/2 dimensional particle-in-cell plasma simulations to study the interaction of a relativistic, strongly magnetized wind with an ambient medium. Such an interaction is a plausible mechanism which leads to generation of cosmological…
Clusters of galaxies are among the best candidates for particle acceleration sources in the universe, a signature of which is non-thermal hard X-ray emission from the accelerated relativistic particles. We present early results on Suzaku…
A principal candidate for quiescent non-thermal gamma-ray emission from magnetars is resonant inverse Compton scattering in the strong fields of their magnetospheres. This paper outlines expectations for such emission, formed from…
The compact stellar clusters have emerged as particularly promising candidates for cosmic rays (CR) accelerators. The star clusters, recently observed in gamma-rays, are also known sources of non-thermal X-ray emission, which is due to…
Models for the integrated relativistic electron population in clusters of galaxies are presented. The results depend on the history of electron acceleration in the cluster. If there is no present particle acceleration or other sources, then…
We show how non-radial motions, originating in the outskirts of clusters of galaxies, may reduce the discrepancy between the Cold Dark Matter (CDM) predicted X-ray temperature distribution function of clusters of galaxies and the observed…
We investigate a scenario where the recently discovered non-thermal hard X-ray emission from the Ophiuchus cluster originates from inverse Compton scattering of energetic electrons and positrons produced in weakly interacting dark matter…
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…
From the hundreds of gamma-ray pulsars known, only a handful show non-thermal X-ray pulsations. Instead, nine objects pulse in non-thermal X-rays but lack counterparts at higher energies. Here, we present a physical model for the…
Hard, non-thermal, persistent pulsed X-ray emission extending between 10 keV and $\sim 150$ keV has been observed in nearly ten magnetars. For inner-magnetospheric models of such emission, resonant inverse Compton scattering of soft thermal…
A two-dimensional electrodynamic model is used to study particle acceleration and non-thermal emission mechanisms in the pulsar magnetospheres. We solve distribution of the accelerating electric field with the emission process and the…
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 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…
Synchrotron radiation mechanism, when electrons are accelerated in a relativistic shock, is known to have serious problems to explain the observed gamma-ray spectrum below the peak for most Gamma-Ray Bursts (GRBs); the synchrotron spectrum…
The paradigm for Anomalous X-ray Pulsars (AXPs) has evolved recently with the discovery by INTEGRAL and RXTE of flat, hard X-ray components in three AXPs. These non-thermal spectral components differ dramatically from the steeper…
The search for diffuse non-thermal, inverse Compton (IC) emission from galaxy clusters at hard X-ray energies has been underway for many years, with most detections being either of low significance or controversial. In this work, we…
Detailed information on the physical parameters in the sources of cosmological Gamma-Ray Bursts (GRBs) is obtained from few plausible assumptions consistent with observations. Model-independent requirements posed by these assumptions on the…
Relativistic electron-positron winds with strong magnetic fields are considered as a source of radiation for cosmological $\gamma$-ray bursters. Such a wind is generated by a millisecond pulsar with a very strong magnetic field. An…
We investigate radiatively inefficient accretion flow models for Sgr A*, the supermassive black hole in our Galactic Center, in light of new observational constraints. Confirmation of linear polarization in the submm emission argues for…
We discuss the possibility that a significant contribution of the hard X-ray Background is the integrated emission from a population of galaxies undergoing advection-dominated accretion in their nuclei. Owing to poor coupling between ions…