Production Of High Energy Cosmic Rays Research Articles

High-energy cosmic ray production in X-ray binary jets

ABSTRACT As smaller analogues of active galactic nuclei, X-ray binaries (XRBs) are also capable of launching jets that accelerate particles to high energies. In this work, we re-examine XRB jets as potential sources of high-energy cosmic rays (CRs) and explore whether they could provide a significant second Galactic component to the CR spectrum. In the most intriguing scenario, XRB-CRs could dominate the observed spectrum above the so-called knee feature at ∼3 × 1015 eV, offering an explanation for several key issues in this transition zone from Galactic to extragalactic CRs. We discuss how such a scenario could be probed in the near future via multimessenger observations of XRB jets, as well as diffuse Galactic neutrino flux measurements.

AN ALL-SKY SEARCH FOR THREE FLAVORS OF NEUTRINOS FROM GAMMA-RAY BURSTS WITH THE ICECUBE NEUTRINO OBSERVATORY

ABSTRACT We present the results and methodology of a search for neutrinos produced in the decay of charged pions created in interactions between protons and gamma-rays during the prompt emission of 807 gamma-ray bursts (GRBs) over the entire sky. This three-year search is the first in IceCube for shower-like Cherenkov light patterns from electron, muon, and tau neutrinos correlated with GRBs. We detect five low-significance events correlated with five GRBs. These events are consistent with the background expectation from atmospheric muons and neutrinos. The results of this search in combination with those of IceCube’s four years of searches for track-like Cherenkov light patterns from muon neutrinos correlated with Northern-Hemisphere GRBs produce limits that tightly constrain current models of neutrino and ultra high energy cosmic ray production in GRB fireballs.

Power-law partition and entropy production of high-energy cosmic rays: Knee-ankle structure of the all-particle spectrum

A statistical description of the all-particle cosmic-ray spectrum is given in the to interval. The high-energy cosmic-ray flux is modeled as an ultra-relativistic multi-component plasma, whose components constitute a mixture of nearly ideal but nonthermal gases of low density and high temperature. Each plasma component is described by an ultra-relativistic power-law density manifested as spectral peak in the wideband fit. The “knee” and “ankle” features of the high– and ultra-high–energy spectrum turn out to be the global and local extrema of the double-logarithmic E3-scaled flux representation in which the spectral fit is performed. The all-particle spectrum is covered by recent data sets from several air shower arrays, and can be modeled as three-component plasma in the indicated energy range extending over six decades. The temperature, specific number density, internal energy and entropy of each plasma component are extracted from the partial fluxes in the broadband fit. The grand partition function and the extensive entropy functional of a non-equilibrated gas mixture with power-law components are derived in phase space by ensemble averaging.

On the extragalactic jet asymmetry and composition, and the production of high energy cosmic rays

We probe the role of the directional asymmetry between relativistic outflows to kilo-parsec scale jets in the propagation and acceleration of cosmic rays. Our sample contains powerful AGN hosting dense cluster environments. We attempt a thorough description of where and when ultra high energy cosmic ray production and acceleration takes place also using radio observations of the large scale structure of the AGNs and X-ray data of the hot dense gas in which the AGNs are situated. As far as the cosmic ray primaries are concerned, the presence of relativistic protons or mildly relativistic electrons/positrons contributes substantially to the energy budget of the jets enabling them to heat efficiently the intracluster gas.

Shock-wave and plasma-pinch mechanisms of galactic cosmic-ray production

Based on recent discoveries, we show that it is appropriate to complement the standard shock-wave model for the production of galactic cosmic rays by a plasma-pinch model. The latter describes well the production of high-energy cosmic rays, yields a simple formula for their intensity, and allows the threshold pattern of the knee-type kink in the secondary particle spectrum and a number of unusual phenomena observed above the threshold to be explained.

Compressible fluctuations in an equatorial pulsar wind and a scenario for wisps in the central Crab nebula

A pulsar wind is expected to be inhomogeneous and intermixed with disturbances originating from the central pulsar in terms of dynamic, electromagnetic and thermal properties. We examine, in this paper, basic properties of two-dimensional compressible perturbations in a magnetized equatorial pulsar wind. Asymptotic solutions at large radii for both fast and slow disturbances in a relativistic magnetohydrodynamic (RMHD) wind are derived analytically. We describe the process of forming RMHD shocks in a pulsar wind with inhomogeneous wind streams emanating from the spinning pulsar and with interlaced, alternately reversed, spiral magnetic field stripes resulting from a pulsar whose rotation and magnetic axes misalign. Spiral bands of forward-reverse shock pairs are expected to appear frequently in a magnetically striped pulsar wind within a certain latitude range about the rotation equator. In highly compressed regions between forward and reverse shocks, magnetized pulsar wind flow could become turbulent so that extremely relativistic particles can be produced in profusion and be injected into the surrounding nebula. Based on our analysis and physical considerations, we propose a scenario for the appearance of wisps in the inner Crab nebula, in which the pattern of inward propagating RMHD fast waves and/or shocks (relative to the pulsar wind) gives rise to the quasi-stationary structure of wisps in the inner Crab nebula, while outward propagating RMHD fast and slow disturbances appear as transients in the sidereal reference frame. The fine wisp region ( ~ 1016 cm) across a strong RMHD reverse shock can squeeze ~ 106_107 magnetic stripes with opposite polarities; magnetic reconnections proceed turbulently therein and lead to dramatic enhancement of relativistic particle acceleration at the expense of flow and magnetic energies continuously supplied from upstream. These processes could also contribute to the production of high-energy cosmic rays.

Monte Carlo simulations of particle acceleration at oblique shocks

The Fermi shock acceleration mechanism may be responsible for the production of high-energy cosmic rays in a wide variety of environments. Modeling of this phenomenon has largely focused on plane-parallel shocks, and one of the most promising techniques for its study is the Monte Carlo simulation of particle transport in shocked fluid flows. One of the principal problems in shock acceleration theory is the mechanism and efficiency of injection of particles from the thermal gas into the accelerated population. The Monte Carlo technique is ideally suited to addressing the injection problem directly, and previous applications of it to the quasi-parallel Earth bow shock led to very successful modeling of proton and heavy ion spectra, as well as other observed quantities. Recently this technique has been extended to oblique shock geometries, in which the upstream magnetic field makes a significant angle Theta(sub B1) to the shock normal. Spectral resutls from test particle Monte Carlo simulations of cosmic-ray acceleration at oblique, nonrelativistic shocks are presented. The results show that low Mach number shocks have injection efficiencies that are relatively insensitive to (though not independent of) the shock obliquity, but that there is a dramatic drop in efficiency for shocks of Mach number 30 or more as the obliquity increases above 15 deg. Cosmic-ray distributions just upstream of the shock reveal prominent bumps at energies below the thermal peak; these disappear far upstream but might be observable features close to astrophysical shocks.

Monte Carlo Simulations of Particle Acceleration at Oblique Shocks

AbstractThe Fermi shock acceleration mechanism may be responsible for the production of high-energy cosmic rays in a wide variety of environments. Modeling of this phenomenon has largely focused on plane-parallel shocks, and one of the most promising techniques for its study is the Monte Carlo simulation of particle transport in shocked fluid flows. One of the principal problems in shock acceleration theory is the mechanism and efficiency of injection of particles from the thermal gas into the accelerated population. The Monte Carlo technique is ideally suited to addressing the injection problem directly, and previous applications of it to the quasi-parallel Earth bow shock led to very successful modeling of proton and heavy ion spectra, as well as other observed quantities. Recently this technique has been extended to oblique shock geometries, in which the upstream magnetic field makes a significant angle ΘB1 to the shock normal. In this paper, spectral results from test particle Monte Carlo simulations of cosmic-ray acceleration at oblique, nonrelativistic shocks are presented. The results show that low Mach number shocks have injection efficiencies that are relatively insensitive to (though not independent of) the shock obliquity, but that there is a dramatic drop in efficiency for shocks of Mach number 30 or more as the obliquity increases above 15°. Cosmic-ray distributions just upstream of the shock reveal prominent bumps at energies below the thermal peak; these disappear far upstream but might be observable features close to astrophysical shocks.Subject headings: acceleration of particles — cosmic rays — shock waves

Stellar and solar flares

Some ideas are developed concerning solar flares which have been presented earlier by the author (Schatzman, 1966a). Emphasis is laid on the problem of energy transport; from the energy supply to the region of the optical flare, on the storage of low energy cosmic ray particles in a magnetic bottle before the beginning of the optical flare, and the mechanism which triggers both the optical flare, and the production of high-energy cosmic rays. The relation between solar and stellar flares is considered.