Related papers: High Energy Gamma Rays from Protons Hitting Compac…
This paper is dedicated to the study how HE particle spectra, which are measured in cosmic ray physics and astrophysics, are influenced by the specifics of collider spectrum of protons.LHC experiments are providing us with the proton…
Ground-based gamma ray observations of the Galactic Center region have revealed a high energy gamma ray source spatially coincident with the gravitational centroid of our Galaxy. The pointlike emission detected by H.E.S.S. exhibits an…
The observations of the total electronic component and the positron fraction in cosmic rays by the FERMI, HESS, ATIC, and PAMELA instruments are studied with analytical propagation models, both for a set of discrete sources and for a…
High-energy cosmic-ray electrons reveal some remarkable spectral features, the most noteworthy of which is the rise in the positron fraction above 10~GeV. Due to strong energy loss during propagation, these particles can reach Earth only…
The GAMMA-400 gamma-ray telescope is intended to measure the fluxes of gamma rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern with the following scientific goals: search…
The clustering of ultra high energy (above 10^20 eV) cosmic rays (UHECR) suggests that they might be emitted by compact sources. Statistical analysis of Dubovsky et al. (Phys. Rev. Lett. 85 (2000) 1154) estimated the source density. We…
The accretion of matter onto intermediate polar White Dwarfs (IPWDs) seems to provide attractive conditions for acceleration of particles to high energies in a strongly magnetized turbulent region at the accretion disk inner radius. We…
Scattering relativistic electrons with optical lasers can result in a significant frequency upshift for the photons, potentially producing $\gamma$-rays. This is what linear Compton scattering taught us. Ultra-intense lasers offer nowadays…
Within a multicomponent dark matter scenario, novel gamma-ray signals may arise from the decay of the heavier dark matter component into the lighter. For a scalar dark sector of this kind, the decay $\phi_2\rightarrow\phi_1 \gamma$ is…
We discuss the origin of continuum and line X-ray emission observed in the direction the Galactic Center. We predict a significant flux of de-excitation gamma-ray lines in this direction, which can be produced by subrelativistic protons…
The 511 keV gamma-ray emission from the galactic center region may fully or partially originate from the annihilation of positrons from dark matter particles with electrons from the interstellar medium. Alternatively, the positrons could be…
Observations of gamma-ray bursts by the Fermi satellite, capable of detecting photons in a very broad energy band: 8keV to >300GeV, have opened a new window for the study of these enigmatic explosions. It is widely assumed that photons of…
One of the major goals of research for laser-plasma accelerators is the realization of compact sources of femtosecond X-rays. In particular, using the modest electron energies obtained with existing laser systems, Compton scattering a…
A gamma-ray excess over background has been claimed in the inner regions of the Galaxy, triggering some excitement about the possibility that the gamma rays originate from the annihilation of dark matter particles. We point out that the…
Recently, gamma-ray emission in the direction of Coma, with a TS value of $\sim 40$, has been reported. In this work we will discuss the possibility of such a residual emission coming from dark matter annihilation. Our results show that the…
Various studies have implied the existence of a gaseous halo around the Galaxy extending out to 100 kpc. Galactic cosmic rays (CRs) that propagate to the halo, either by diffusion or by convection with the possibly existing large-scale…
One prediction of particle acceleration in the supernova remnants in the magnetic wind of exploding Wolf Rayet and Red Super Giant stars is that the final spectrum is a composition of a spectrum $E^{-7/3}$ and a polar cap component of…
Secondary nuclear production physics is receiving increased attention given the high-quality measurements of the gamma-ray emissivity of local interstellar gas between ~50 MeV and ~40 GeV, obtained with the Large Area Telescope on board the…
If dark matter decays or annihilates into electrons and positrons, it can affect radiation and cosmic-ray backgrounds. We review a novel, more general analysis of constraints on decaying dark matter models, by introducing the response…
We propose that repeated photoexcitation/ionization of high Z atoms of highly relativistic flows by star light in dense stellar regions followed by emission of decay/recombination photons, which are beamed and boosted to gamma ray energies…