Pondermotive acceleration of charged particles along the relativistic jets of an accreting blackhole

Accreting blackholes such as miniquasars and active galactic nuclei can contribute to the highest energy components of intra- (～10¹⁵?eV) galactic and extra-galactic components (～10²⁰?eV) of cosmic rays. Alfven wave pulses which are excited in the accretion disk around blackholes propagate in relativistic jets. Because of their highly non-linear nature of the waves, charged particles (protons, ions, and electrons) can be accelerated to high energies in relativistic jets in accreting blackhole systems, the central engine of miniquasars and active galactic nuclei.     

Cosmic rays from the knee to the highest energies

This review summarizes recent developments in the understanding of high-energy cosmic rays. It focuses on galactic and presumably extragalactic particles in the energy range from the knee (10¹⁵ eV ) up to the highest energies observed (>10²⁰ eV). Emphasis is put on observational results, their interpretation, and the global picture of cosmic rays that has emerged during the last decade.     

Arrival directions and chemical composition of ultrahigh-energy cosmic rays

Chemical composition of ultrahigh-energy cosmic rays is estimated through the reliably determined (both experimentally and theoretically) distribution of the number of showers in the galactic latitude. Experimental data at energies of ～10¹⁹ eV agree with the theoretical calculations, provided that cosmic rays involve predominantly heavy nuclei. An enhanced flux of cosmic rays from the galactic plane is detected at energies of ～10¹⁹ eV.     

On the Acceleration of Energetic Cosmic Particles by Electrostatic Double Layers

The capability of electrostatic double layers of accelerating charged particles to high energies is investigated. Starting from a one-dimensional relativistic double-layer model a two-dimensional relativistic double layer in a current filament is studied. It is found that the filamentary double layer has a maximum potential drop that depends both on the magnitude of the filamentary current and on the composition of the layer. The results are applied to two cosmic double layers?one in a solar electric circuit and another in a galactic circuit. If the layers are composed of protons and electrons, these particles may be accelerated to 1011 eV in the solar layer and to 1014 eV in the galactic layer. It is suggested that the solar double layer may account for the acceleration of solar cosmic rays while the galactic layer may contribute to the generation of cosmic radiation.     

Composition of cosmic rays accelerated in supernova remnants

The kinetic theory of regular acceleration of cosmic rays in supernova remnants is used to investigate the expected chemical composition of the rays. It is shown that the shapes of the calculated profiles of the chemical elements making up the cosmic rays are consistent with experiment wherever the results of measurements are available. The acceleration process is accompanied by relative enrichment of the cosmic rays with heavy elements. If the analogous property of the mechanism underlying the injection of superthermal particles into the acceleration regime is taken into account, such enrichment supports the formation of the required composition of cosmic rays in the energy range up to 10¹⁴–10¹⁵ eV. Zh. éksp. Teor. Fiz. 116, 737–759 (September 1999)     

Primary cosmic ray composition at energies from 10<Superscript>17</Superscript> to 10<Superscript>18</Superscript> eV according to the EAS MSU array data

EAS MSU array data on the composition of primary cosmic rays at energies above 10₁₇ eV are analyzed. The problem of existence of a cosmic ray component that is not related to the conventional mechanism of formation of galactic cosmic rays is considered and the fraction of γ rays in primary cosmic rays is estimated.     

A Statistic Model for Galactic Cosmic Rays

Supposed that all of cosmic ray particles of energy below 3×10¹⁸eV are mainly originated and accelerated in an individual explosion of the galactic supernovae(SNs).By using an isotropic diffusion propagation model,non-steady state density of the iron nucleus is investigated.Considering the effect of extra-galactic cosmic rays and the variety of the galactic cosmic ray nuclei,the statistic model of galactic cosmic rays with a reasonable distribution of the SNs in space and time can account for the spectrum of cosmic ray in the energy range of 10¹²—10²⁰eV quitewell.     

Investigation of gamma-ray families originating from nucleus-nucleus interactions at ultrahigh energies E 0 in excess of 1016 eV

Various spatial and energy features of gamma-ray families originating from the interactions of primary nuclei of galactic cosmic rays with nuclei of atmospheric atoms (AA interactions) are studied. The mass composition of galactic cosmic rays is analyzed on the basis of data from x-ray emulsion chambers of the Pamir experiment with the aid of a criterion for selecting gamma-ray families originating from AA interactions (A families) at energies E ₀ of primary galactic cosmic rays in excess of 10¹⁶ eV. According to the results obtained in this way only the experimental spatial parameters R _1E and ρ differ from their counterparts in the MC0 model.     

Particle acceleration at astrophysical shocks: A theory of cosmic ray origin

The theory of first order Fermi acceleration at collisionless astrophysical shock fronts is reviewed. Observations suggest that shock waves in different astrophysical environments accelerate cosmic rays efficiently. In the first order process, high energy particles diffuse through Alfvén waves that scatter them and couple them to the background plasma. These particles gain energy, on the average, every time they cross the schock front and bounce off approaching scattering centers. Calculations demonstrate that the distribution function transmitted by a plane shock is roughly a power law in momentum with slope similar to that inferred in galactic cosmic ray sources. The generation of the scattering Alfvén waves by the streaming cosmic rays is described and it is argued that the wave amplitude is probably non-linear within sufficiently strong astrophysical shocks. Hydromagnetic scattering can operate on the thermal particles as well, possibly establishing the shock structure. This suggests a model of strong collisionless shocks in which high energy particles are inevitably produced very efficiently. Observable consequences of this model, together with its limitations and some alternatives, are described. Cosmic ray origin and astrophysical shocks can no longer be considered separately.     

Neutrino—nucleon cross-section at ultra-high energies in models with large extra dimensions

We examine whether the models with large extra dimensions can provide an explanation for the GZK violating ultra-high energy cosmic rays (UHECR). In these models the neutrino—nucleon cross-section rises rapidly with energy and hence cosmic rays might be identified with neutrinos. We calculate the neutrino-nucleon cross-section at ultra high energies by assuming that it is dominated by the production ofp-branes. We perform the calculation in a generalized Randall-Sundrum model and Lykken-Randall model and find cross-sections of the order of 100 mb at neutrino energies of 10²⁰ eV, which is required for explaining UHECR events.     

Search for extragalactic sources of ultrahigh-energy cosmic rays

Possible extragalactic sources of cosmic rays with energies above 4 × 10¹⁹ eV detected at the Yakutsk EAS array are sought. The correlation of the shower arrival directions with objects from Véron’s catalog that are located closer than 100 Mpc from the Earth confirms the observations at the Pierre Auger Observatory, as well as the Greisen-Zatsepin-Kuzmin effect on the spectrum of cosmic rays. The detailed analysis of the data reveals the classes of objects belonging to the active galactic nuclei that are the most probable sources of ultrahigh-energy cosmic rays.     

Ultra high energy cosmic rays: Identification of possible sources, energy spectra, and propagation

This review is devoted to the problem of the origin of cosmic rays (CR) with energy E >4 × 10¹⁹ eV. The review mainly deals with the hypothesis of CR acceleration in active galactic nuclei (AGN). The review consists of the following five sections: Introduction, three chapters, and Conclusions. The following points are considered in Introduction: shower arrays for detecting ultra high energy cosmic rays (UHECR), the Greisen-Zatsepin-Kuzmin (GZK) cutoff, and the hypotheses of the UHECR origin. Since CRs are of extraterrestrial origin, some astrophysical data used in CR physics are presented in a special section. The identification of UHECR sources with energies E > 4 × 10¹⁹ eV is analyzed in Chapter 2. Chapter 3 deals with CR acceleration in sources and CR escape from sources. Chapter 4 is devoted to particle propagation in intergalactic space with allowance for CR interaction with the microwave background radiation and energy losses (blackbody or GZK cutoff). The propagation of UHECR protons is analyzed and their spectra at the Earth are calculated numerically. In Conclusions, we formulate the results and list the nuclear data needed to develop the model in more detail, namely, to study the propagation of CR nuclei in intergalactic space and to analyze the UHECR composition at the Earth.     

Some recent developments in cosmic rays

Recent work on the energy spectrum, composition and anisotropy of the primary cosmic ray flux from about 10⁹ eV to 10²⁰ eV is summarized, together with related information on phonons between 1 MeV and 200 MeV. Solar particles are not discussed, the emphasis being on topics bearing on the origin of the radiation, which is still an unsolved problem, although the probabilities are strongly in favour of an entirely galactic origin for the particles. Mechanisms of acceleration are not discussed.     

Possible attenuation of the radio signal from the cascade in solid medium at energies above 1020 eV

It was shown that the effect of plasma production during solid medium ionization by a developing cascade can shield excess-charge radiation in the radio range used for detecting particles at energies higher than 10²⁰ eV. Such a shielding effect is significant in Antarctic ice and is insignificant for lunar regolith. Hence, the LORD experiment on detection of cascades from ultrahigh-energy cosmic rays and neutrinos from circumlunar spacecrafts retains the capability of measurements up to the energies of 10²³ eV.     

Cosmic ray energy spectrum from measurements of air showers

This review focuses on high-energy cosmic rays in the PeV energy range and above. Of particular interest is the knee of the spectrum around 3 PeV and the transition from cosmic rays of Galactic origin to particles from extra-galactic sources. Our goal is to establish a baseline spectrum from 1014 to 10^20 eV by combining the results of many measurements at different energies. In combination with measurements of the nuclear composition of the primaries, the shape of the energy spectrum places constraints on the number and spectra of sources that may contribute to the observed spectrum.     

Ultimate energy of cosmic rays generated in supernova shells

It is shown that the ultimate energy of cosmic rays accelerated in a supernova shell due to the surfing acceleration mechanism is determined by the shell radius and the interstellar magnetic field. The ultimate energy of cosmic rays accelerated in the supernova shock does not exceed 10¹⁷ eV for typical values of the interstellar magnetic field in the vicinity of a supernova and the radii of observed supernova shells.     

On the attenuation of radio Cherenkov radiation from a cascade in a solid medium at ultrahigh energies

It is shown that the effect of the formation of electron-hole plasma during ionization of a solid mediumby a cascade developing in it can shield charge-excess Cherenkov radiation in the radio range used for detecting particles by radio detectors at energies above 10²⁰ eV. Such a shielding effect is strong in pure Antarctic ice and is weaker in lunar regolith; hence, the LORD experiment on the detection of cascades from ultrahigh-energy cosmic rays and neutrinos by circumlunar apparatuses retains the possibility of detecting particles to energies of ∼3 · 10²⁰ eV.     

Diffusion of cosmic rays in a model with interstellar turbulence damping due to interaction with energetic particles

A self-consistent model of galactic cosmic ray transport is considered. The resonance wave–particle interaction in this model causes a cascade of magnetosonic waves to decay in the interstellar medium. The calculated coefficient of diffusion of cosmic rays in the Galaxy has a characteristic minimum at an energy of several GeV/nucleon, which agrees with the empirical diffusion model of cosmic ray propagation.     

Study of the energy spectrum and mass composition of primary cosmic rays in the energy range of 10<Superscript>18</Superscript>–10<Superscript>20</Superscript> eV using a balloon setup in antarctica (SPHERE-antarctica project)

An Antarctic balloon experiment for measuring the energy spectrum and elemental composition of cosmic rays in the ultrahigh-energy range (10¹⁸–10²⁰) eV is proposed. Scientific equipment will measure fluorescence caused by an extensive air shower formed in the atmosphere by an ultrahigh energy particle and Cherenkov light of this shower reflected from a snow surface. It is assumed that the balloon will fly in the circumpolar orbit in Antarctica at a height of ~25 km for (2–3) winter (in the Southern Hemisphere)months. For this time, ~3000 events caused by particles with energies above 10¹⁸ eV and (200–300) events caused by particles with energies above 10¹⁹ eV will be detected.