نتایج جستجو برای: cosmic ray nucleus
تعداد نتایج: 432120 فیلتر نتایج به سال:
A recent re-determination of the non-thermal component of the hard X-ray to soft γ-ray emission from the Galactic ridge, using the SPI instrument on the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) Observatory, is shown to be well reproduced as inverse-Compton emission from the interstellar medium. Both cosmic-ray primary electrons and secondary electrons and positrons contribute ...
We present preliminary results of Particle-In-Cell simulations of magnetic turbulence production by isotropic cosmic-ray ions streaming upstream of supernova remnant shocks. The studies aim at testing the MHD predictions by Bell [1, 2] of a strong amplification of short-wavelength nonresonant wave modes and at studying the subsequent evolution of the magnetic turbulence and its backreaction on ...
As accretion and merger shocks in clusters of galaxies may accelerate particles to high energies, clusters are candidate sites for the origin of ultra-high-energy (UHE) cosmic-rays. Recently, a prediction was presented for gamma-ray emission from a cluster of galaxies at a detectable level with modern imaging atmospheric Cherenkov telescopes. The gamma-ray emission was produced via inverse Comp...
A new calculation of the Galactic diffuse gamma-ray spectrum from the decay of secondary particles produced by interactions of cosmic-ray protons with interstellar matter is presented. The calculation utilizes the modern Monte Carlo event generators, Hadrin, Fritiof and Pythia, which simulate high-energy proton-proton collisions and are widely used in studies of nuclear and particle physics, in...
Supernova remnants interacting with molecular clouds are potentially exciting systems in which to detect evidence of cosmic ray acceleration. Prominent γ-ray emission is produced via the decay of neutral pions when cosmic rays encounter the nearby dense clouds. In many of the supernova remnants coincident with γ-ray sources, the presence of OH(1720 MHz) masers is used to identify interaction wi...
The global processes that determine cosmic ray modulation are reviewed. The essential elements of the theory which describes cosmic ray behavior in the heliosphere are summarized, and a series of discussions is presented which compare the expectations of this theory with observations of the spatial and temporal behavior of both galactic cosmic rays and the anomalous component; the behavior of c...
Assuming that refractory elements in cosmic rays originate in dust grains, we examine the viability of cosmic ray origin models wherein the bulk of present day cosmic rays are accelerated out of fresh supernova ejecta material before it mixes with the average interstellar medium (ISM). We conclude that the fresh ejecta scenarios that have been proposed thus far have serious flaws, and are unabl...
We address some current theoretical issues around ultra-high energy cosmic rays. We recall that scenarios producing more γ−rays than cosmic rays up to high redshift can in general only provide a sub-dominant contribution to the ultra-high energy cosmic ray flux. This includes extra-galactic top-down and the Z-burst scenarios. Finally we discuss the influence of large scale cosmic magnetic field...
We employ the Monte Carlo particle collision code DPMJET3.04 to determine the multiplicity spectra of various secondary particles (in addition to π 0 's) with γ's as the final decay state, that are produced in cosmic-ray (p's and α's) interactions with the interstellar medium. We derive an easy-to-use γ-ray production matrix for cosmic rays with energies up to about 10 PeV. This γ-ray productio...
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