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It is shown that the acceleration of particles by a powerful relativistic jet associated with the activity of a supermassive black hole in the Galactic center several million years ago may explain the observed cosmic ray spectrum at energies higher than $10^{15}$ eV. The accelerated particles are efficiently confined in the extended magnetized gas halo created by the supernova and central black hole activity just after the Galaxy formation. We found that both the heavy and light chemical composition of ultra-high energy cosmic rays can be consistent with observations., Comment: 24 pages, 8 figures, accepted to Phys. ReV. D

It is shown that the relativistic jets associated with the growth and past activity of the supermassive black hole in the Andromeda galaxy could be the main source of cosmic rays with energies above $10^{15}$ eV. Most of the cosmic ray energy is related to a bow shock of the jet that produces multi-PeV cosmic rays with light composition. The highest energy cosmic rays with heavy composition are produced in the jet itself. The spectra of energetic particles produced in Andromeda galaxy and propagated to the Earth are calculated and compared with observations., Comment: 5 pages, 4 figures, corrected references, published in MNRAS Letters

We consider diffusive shock acceleration in supernova remnants throughout their evolution including a radiative stage. It is found that a more efficient acceleration and fast exit of particles at the radiative stage results in the hardening of the source cosmic ray proton and electron spectra at energies $\sim 100-500$ GeV. The effect is stronger for cosmic ray electrons., Comment: 8 pages, 8 figures, accepted to MNRAS. arXiv admin note: text overlap with arXiv:1701.00844

A wide-angle Cerenkov array TAIGA-HiSCORE (FOV $\sim$0.6 sr), was originally created as a part of TAIGA installation for high-energy gamma-ray astronomy and cosmic ray physics. Array now consist on nearly 100 optical stations on the area of 1 km$^2$. Due to high accuracy and stability ($\sim$1 ns) of time synchronization of the optical stations the accuracy of EAS arrival direction reconstruction is reached 0.1$^\mathrm{o}$. It was proven that the array can also be used to search for nanosecond events of the optical range. The report discusses the method of searching for optical transients using the HiSCORE array and demonstrates its performance on a real example of detecting signals from an artificial Earth satellite. The search for this short flares in the HiSCORE data of the winter season 2018--2019 is carried out. One candidate for double repeater has been detected, but the estimated probability of random simulation of such a transient by background EAS events is not less than 10%, which does not allow us to say that the detected candidate corresponds to a real astrophysical transient. An upper bound on the frequency of optical spikes with flux density of more than $10^{-4} \mathrm{erg/s/cm}^2$ and a duration of more than 5\,ns is established as $\sim 2 \times 10^{-3}$ events/sr/hour., Comment: 15 pages, 6 figures, reported at the conference ISCRA-2021, Accepted for publication in Physics of Atomic Nuclei

The EAS Cherenkov light array Tunka-133, with $\sim$ 3 km$^2$ geometric area, is taking data since 2009.The array permits a detailed study of energy spectrum and mass composition of cosmic rays in the energy range from $6\cdot 10^{15}$ to $10^{18}$ eV. We describe the methods of time and amplitude calibration of the array and the methods of EAS parameters reconstruction. We present the all-particle energy spectrum, based on 7 seasons of operation., Comment: 12 pages,18 figures

We aim to elucidate cosmic ray (CR) propagation in the weakly ionized environments of supernova remnants (SNRs) basing our analysis on the cosmic ray cloud (CRC) model developed by \citet{2013ApJ...768...73M} and \citet{2016MNRAS.461.3552N}. We solved two transport equations simultaneously: one for the CR pressure and one for the Alfv\'en wave energy density where CRs are initially confined in the SNR shock. Cosmic rays trigger a streaming instability and produce slab-type resonant Alfv\'en modes. The self-generated turbulence is damped by ion-neutral collisions and by noncorrelated interaction with Alfv\'en modes generated at large scales. We show that CRs leaking in cold dense phases such as those found in cold neutral medium (CNM) and diffuse molecular medium (DiM) can still be confined over distances of a few tens of parsecs from the CRC center for a few thousand years. At 10 TeV, CR diffusion can be suppressed by two or three orders of magnitude. This effect results from a reduced ion-neutral collision damping in the decoupled regime. We calculate the grammage of CRs in these environments. We find that in both single and multi-phase setups at 10 GeV, CNM and DiM media can produce grammage in the range 10-20 $\rm{g/cm^2}$ in the CNM and DiM phases. At 10 TeV, because of nonlinear propagation the grammage increases to values in the range 0.5-20 $\rm{g/cm^2}$ in these two phases. We also present preliminary calculations in inhomogeneous interstellar medium combining two or three different phases where we obtain the same trends., Comment: 28 pages, 14 figures, accepted in Astronomy and Astrophysics main journal, language edited version

We investigate acceleration of cosmic rays by shocks and accretion flows in galaxy clusters. Numerical results for spectra of accelerated particles and nonthermal emission are presented. It is shown that the acceleration of protons and nuclei in the nearby galaxy cluster Virgo can explain the observed spectra of ultra high energy cosmic rays., Comment: 7 pages, 5 figures, oral talk at the 26th European Cosmic Ray Symposium, Barnaul, Russia, July 6 - 10, 2018

We consider the diffusive shock acceleration in interstellar bubbles created by powerful stellar winds of supernova progenitors. Under the moderate stellar wind magnetization the bubbles are filled by the strongly magnetized low density gas. It is shown that the maximum energy of particles accelerated in this environment can exceed the "knee" energy in the observable cosmic ray spectrum., Comment: 9 pages, 6 figures, corrected version, accepted to Astroparticle Physics

The inverse problem of cosmic ray transport of ultra-high energy cosmic rays is considered. The analysis of Auger data on energy spectrum, energy dependence of mean logarithm of atomic mass number and its variance allows definite conclusions on the shape of the source spectrum in the frameworks of the inverse problem approach. The discussion on regularization procedure for considered ill-posed problem is presented., Comment: XXV ECRS 2016 Proceedings - eConf C16-09-04.3

Nonlinear model of diffusive shock acceleration is used for investigation of the particle acceleration in old supernova remnants W28 and W44. We modeled the hydrodynamical evolution of the remnants, shock modification and streaming instability produced by accelerated particles. Comparison with available radio and gamma-ray data is given., Comment: XXV ECRS 2016 Proceedings - eConf C16-09-04.3, revised version

It is shown that high-energy astrophysical neutrinos observed in the IceCube experiment can be produced by protons accelerated in extragalactic Type IIn supernova remnants by shocks propagating in the dense circumstellar medium. The nonlinear diffusive shock acceleration model is used for description of particle acceleration. We calculate the neutrino spectrum produced by an individual Type IIn supernova and the spectrum of neutrino background produced by IIn supernovae in the expanding Universe. We also found that the arrival direction of one Icecube neutrino candidate (track event 47) is at 1.35$^{\circ }$ from Type IIn supernova 2005bx., Comment: 7 pages, 7 figures, submitted to Astroparticle Physics

It is shown that high-energy astrophysical neutrinos observed in the IceCube experiment can be produced by protons accelerated in extragalactic Type IIn supernova remnants by shocks propagating in the dense circumstellar medium. The nonlinear diffusive shock acceleration model is used for description of particle acceleration., Comment: 9 pages, 4 figures, oral talk at 34th ICRC, Hague, Netherlands 30July-06Aug 2015

The energy spectra and composition of ultra-high energy cosmic rays are changing in a course of propagation in the expanding Universe filled with background radiation. We developed a numerical code for solution of inverse problem for cosmic-ray transport equations that allows the determination of average source spectra of different nuclei from the cosmic ray spectra observed at the Earth. Employing this approach, the injection spectra of protons and Iron nuclei in extragalactic sources are found assuming that only these species are accelerated at the source. The data from the Auger experiment and the combined data from the Telescope Array + HiRes experiments are used to illustrate the method., Comment: 12 pages, 8 figures

In this paper, a probable interpretation of a remarkable fine structure of all particle spectra between the knee and the ankle, as well as a high content of heavy nuclei around 10^17 eV measured recently in Tunka-133 and KASCADE Grande experiments, is presented in the model where production of cosmic rays in Type Ia SNRs provides observed cosmic rays (CR) flux around the knee. Subtracting the contribution of these sources from all particle spectrum we obtained the residual flux of CR in the transition region between Galactic and Extragalactic CR in the range 10^17-5 10^18 eV. The obtained spectrum also has a pronounced knee at energy (2-3)10^17 eV and slopes g1 ~ 1.8+-0.3 below it and g2 ~3.4 above it. We analyzed the possible contribution from known Galactic sources and found that formally the best candidate to contribute significantly to the transition region is Cas A. This source posses a number of unusual properties and considered as Type IIb SNR. However we showed that the hypothesis of extragalactic origin of CR starting from 10^17 eV seems more realistic., Comment: 6 pages, 3 figures

The role of nearby galactic sources, the supernova remnants, in formation of observed energy spectrum and anisotropy of high-energy cosmic rays is studied. The list of these sources is made up based on radio, X-ray and gamma-ray catalogues. The distant sources are treated statistically as ensemble of sources with random positions and ages. The source spectra are defined based on the modern theory of cosmic ray acceleration in supernova remnants while the propagation of cosmic rays in the interstellar medium is described in the frameworks of galactic diffusion model. Calculations of anisotropy are made to reproduce the experimental procedure of getting the two-dimensional anisotropy. The detailed comparison of calculations with cosmic ray data is made. We explained simultaneously the new cosmic ray data on a fine structure of all particle spectra around the knee and the amplitude and direction of the dipole component of anisotropy in the wide energy range 1 TeV - 1 EeV. Made assumptions do not look exotic, and they confirm the modern understanding of cosmic ray origin., Comment: 26 pages, 7 double figures

Data obtained in the ATIC-2 (Advanced Thin Ionization Calorimeter), CREAM (Cosmic Ray Energetics and Mass)) and PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) experiments suggest that elemental interstellar spectra of cosmic rays below the knee at a few times $10^{6}$ GeV are not simple power laws, but they experience hardening at magnetic rigidity above about 240 GV. Another essential feature is the difference between proton and Helium energy spectra, so that the He/p ratio increases by more than 50% in the energy range from $10^{2}$ to $10^{4}$ GV. We consider the concavity of particle spectrum resulting from the nonlinear nature of diffusive shock acceleration in supernova remnants (SNR) as a possible reason for the observed spectrum hardening. Helium-to-proton ratio increasing with energy can be interpreted as a consequence of cosmic ray acceleration by forward and reverse shocks in SNRs. The contribution of particles accelerated by reverse shocks makes the concavity of the produced overall cosmic ray spectrum more pronounced. The spectra of protons and helium nuclei accelerated in SNRs and released into the interstellar medium are calculated. The derived steady state interstellar spectra are in reasonably good agreement with observations., Comment: 18 pages, 2 figures, accepted to ApJ

A new EAS Cherenkov light array, Tunka-133, with ~1 km^2 geometrical area has been installed at the Tunka Valley (50 km from Lake Baikal) in 2009. The array permits a detailed study of cosmic ray energy spectrum and mass composition in the energy range 10^16 - 10^18 eV with a uniform method. We describe the array construction, DAQ and methods of the array calibration.The method of energy reconstruction and absolute calibration of measurements are discussed. The analysis of spatial and time structure of EAS Cherenkov light allows to estimate the depth of the EAS maximum X_max. The results on the all particles energy spectrum and the mean depth of the EAS maximum X_max vs. primary energy derived from the data of two winter seasons (2009 -- 2011), are presented. Preliminary results of joint operation of the Cherenkov array with antennas for detection of EAS radio signals are shown. Plans for future upgrades -- deployment of remote clusters, radioantennas and a scintillator detector network and a prototype of the HiSCORE gamma-telescope -- are discussed., Comment: 8 pages, Proceedings of the RICAP 2011 Conference, submitted to NIM A

A new numerical model of the nonlinear diffusive shock acceleration is presented. It is used for modeling of particle acceleration in supernova remnants. The model contains coupled spherically symmetric hydrodynamic equations and the transport equations for energetic protons, ions and electrons. The forward and reverse shocks are included in the consideration. The spectra of cosmic rays released into interstellar medium from a supernova remnant are determined. The role of the reverse shock in the production of CR ions and positrons is discussed., Comment: 14 pages, 10 figures, accepted to Astroparticle Physics

The cosmic ray source spectrum produced by AGN (Active Galactic Nucleus) jets is calculated. A distinctive feature of these calculations is the account for the jet distribution on kinetic energy. The expected cosmic ray spectrum at the Earth is determined with the use of a simple numerical code which takes into account interactions of ultra-high energy protons and nuclei with the background radiation in an expanding universe., Comment: 16 pages, accepted in Advances in Space Research

The spectra of high-energy protons and nuclei accelerated by supernova remnant shocks are calculated taking into account magnetic field amplification and Alfvenic drift both upstream and downstream of the shock for different types of supernova remnants during their evolution. The maximum energy of accelerated particles may reach $5\cdot10^{18}$ eV for Fe ions in Type IIb SNRs. The calculated energy spectrum of cosmic rays after propagation through the Galaxy is in good agreement with the spectrum measured at the Earth., Comment: 9 pages, 3 figures, accepted to ApJ

The new EAS Cherenkov array Tunka-133 with about 1 km**2 geometric acceptance area is installed in the Tunka Valley (50 km from Lake Baikal). The array willpermit a detailed study of cosmic ray energy spectrum and mass composition in the energy range of 10**15 - 10**18 eV with uniform method. The array consistsof 19 clusters, each composed of 7 optical detectors with 20 cm PMTs. Since November 2008, the first 12 clusters are in operation, commissioning of the whole array is planned for September 2009 (At the time of submission of this paperto electronic arXiv(February 2010) the completed Tunka-133 array is already taking data). We describe the array construction and DAQ, preliminary results and plans for the future development: deployment of radio-antennas and muon detectors network., Comment: 4 pages, 6 figures, Proc. of 31th ICRC, July 7-15, 2009, Lodz, Poland

The spectra of high-energy protons and nuclei accelerated by supernova remnant shocks are calculated taking into account magnetic field amplification and Alfvenic drift for different types of SNRs during their evolution. The overall energy spectrum and elemental composition of cosmic rays after propagation through the Galaxy are found., Comment: 4 pages, 4 figures, talk presented at 31st ICRC, Lodz, Poland, July 2009

The final analysis of the Extensive Air Shower (EAS) maximum X_max depth distribution derived from the data of Tunka-25 atmospheric Cherenkov light array in the energy range 3.10^15 - 3.10^16 eV is presented. The perspectives of X_max studies with the new Cherenkov light array Tunka-133 of 1 km^2 area, extending the measurements up to 10^18 eV, are discussed., Comment: 6 pages, 7 figures, Proceedings of CRIS 2008 - Cosmic Ray International Seminar - Malfa, Salina Island, Eolian Islands, Italy, September 15 - 19, 2008, to be published in Nucl. Phys. B (Proc. Suppl.), 2009

Cosmic ray acceleration in SNRs in the presence of the Alfv\'enic drift is considered. It is shown that spectra of accelerated particles may be considerably softer in the presence of amplified magnetic fields., Comment: 4 pages, 4 figures, poster talk at 4-th Gamma-ray Symposium (Heidelberg, Germany, 7-11th of July 2008)

The new EAS Cherenkov array TUNKA-133, with about 1 km**2 sensitive area, is being installed in the Tunka Valley. The investigated energy range is 10**15-10**18 eV. It will consist of 133 optical detectors based on EMI9350 PMTs. Optical detectors are grouped into 19 clusters with 7 detectors each. The detectors are connected to the cluster box with RG-58 cables. Every PMT signal is digitized in the cluster box with 200 MHz FADC. The cluster boxes are connected to the data acquisition center with a 1 Gb/s optical link. A detailed description of the data acquisition system (DAQ) is presented., Comment: 5 pages, 4 figures, Proceedings of the 10th ICATPP Conference,Como Italy, 8-12 October 2007

We have studied the non-resonant streaming instability of charged energetic particles moving through a background plasma, discovered by Bell (2004). We confirm his numerical results regarding a significant magnetic field amplification in the system. A detailed physical picture of the instability development and of the magnetic field evolution is given., Comment: 12 pages, 4 figures, accepted to ApJ

We investigate the diffusive shock acceleration in the presence of the non-resonant streaming instability introduced by Bell (2004). The numerical MHD simulations of the magnetic field amplification combined with the analytical treatment of cosmic ray acceleration permit us to calculate the maximum energy of particles accelerated by high-velocity supernova shocks. The estimates for Cas A, Kepler, SN1006, and Tycho historical supernova remnants are given. We also found that the amplified magnetic field is preferentially oriented perpendicular to the shock front downstream of the fast shock. This explains the origin of the radial magnetic fields observed in young supernova remnants., Comment: 18 pages, 9 figures, accepted to ApJ

The new EAS Cherenkov array Tunka-133, with about 1 km**2 sensitive area, is being installed in the Tunka Valley since the end of 2005. This array will permit a detailed study of the cosmic ray energy spectrum and the mass composition in the energy range of 10**15-10**18 eV with a unique method. The array will consist of 19 clusters, each composed of 7 optical detectors. The first cluster started operation in October 2006. We describe the data acquisition system and present preliminary results from data taken with the first cluster., Comment: 4 pages, 4 figures, Proceedings of 30th ICRC, Merinda, Mexico, July 2007

The project of an EAS Cherenkov array in the Tunka valley/Siberia with an area of about 1 km2 is presented. The new array will have a ten times bigger area than the existing Tunka-25 array and will permit a detailed study of the cosmic ray energy spectrum and the mass composition in the energy range from 10^15 to 10^18 eV., Comment: 4 pages, 2 figures, ICRC2005, rus-kuzmichev-LA-abs1-he15-poster

The physical processes involved in diffusion of Galactic cosmic rays in the interstellar medium are addressed. We study the possibility that the nonlinear MHD cascade sets the power-law spectrum of turbulence which scatters charged energetic particles. We find that the dissipation of waves due to the resonant interaction with cosmic ray particles may terminate the Kraichnan-type cascade below wavelengths 10^13 cm. The effect of this wave dissipation has been incorporated in the GALPROP numerical propagation code in order to asses the impact on measurable astrophysical data. The energy-dependence of the cosmic-ray diffusion coefficient found in the resulting self-consistent model may explain the peaks in the secondary to primary nuclei ratios observed at about 1 GeV/nucleon., Comment: 15 pages, 20 figures, 1 table, emulateapj.cls; To be published in ApJ 10 May 2006, v.642

The cosmic-ray streaming instability creates strong magnetohydrodynamic turbulence in the precursor of a SN shock. The level of turbulence determines the maximum energy of cosmic-ray particles accelerated by the diffusive shock acceleration mechanism. The present consideration continues our work Ptuskin & Zirakashvili (2003). It is assumed that the Kolmogorov type nonlinear wave interactions together with the ion-neutral collisions restrict the amplitude of random magnetic field. As a result, the maximum energy of accelerated particles strongly depends on the age of a SNR. The average spectrum of cosmic rays injected in the interstellar medium over the course of adiabatic SNR evolution (the Sedov stage) is approximately $Q(p)p^{2}\propto p^{-2}$ at energies larger than 10-30 Gev/nucleon and with the maximum particle energy that is close to the knee position in cosmic ray spectrum observed at $\sim4\times10^{15}$ eV. At earlier stage of SNR evolution - the ejecta dominated stage described by the Chevalier-Nadyozhin solution, the particles are accelerated to higher energies and have rather steep power-law distribution on momentum. These results suggest that the knee may mark the transition from the ejecta-dominated to the adiabatic evolution of SNR shocks which accelerate cosmic rays., Comment: 12 pages, 2 figures, LATEX

We study the production of cosmic rays (CRs) in supernova remnants (SNRs), including the reacceleration of background galactic cosmic rays (GCRs) - thus refining the early considerations by Blandford & Ostriker (1980) and Wandel et al. (1987) - and the effects of the nuclear spallation inside the sources (the SNRs). This combines for the first time nuclear spallation inside CR sources and in the diffuse interstellar medium, as well as reacceleration, with the injection and subsequent acceleration of suprathermal particles from the postshock thermal pool. Selfconsistent CR spectra are calculated on the basis of the nonlinear kinetic model. It is shown that GCR reacceleration and CR spallation produce a measurable effect at high energies, especially in the secondary to primary (s/p) ratio, making its energy-dependence substantially flatter than predicted by the standard model. Quantitatively, the effect depends strongly upon the density of the surrounding circumstellar matter. GCR reacceleration dominates secondary CR production for a low circumstellar density. It increases the expected s/p ratio substantially and flattens its spectrum to an almost energy-independent form for energies larger than 100 GeV/n if the supernovae explode on average into a hot dilute medium with hydrogen number density $N_H=0.003$cm$^{-3}$. The contribution of CR spallation inside SNRs to the s/p ratio increases with increasing circumstellar density and becomes dominant for $N_H\gsim 1$ cm$^{-3}$, leading at high energies to a flat s/p ratio which is only by a factor of three lower than in the case of the hot medium. Measurements of the boron to carbon ratio at energies above 100 GeV/n could be used in comparison with the values predicted here as a consistency test for the supernova origin of the GCRs., Comment: 11 pages, 6 figures, accepted for publication in Astronomy and Astrophysics