The differential energy spectrum of the cosmic radiation from solar modulation energies up to 5x10**19 eV is correctly predicted by a recent theory of the knee and ankle which uses only one normalization point. This remarkable quantitative result, spanning over many decades in energy and intensity, along with the existence of the second knee at 6x10**17 eV, is obtained assuming constant spectral indices of individual ions at the cosmic-ray sources and no other critical hypotheses. In this study the chemical composition of the cosmic radiation is evaluated as a direct consequence of the theory. The computed mean logarithmic mass exhibits a rising trend from 1.8 to 3.0 in the range 10**15-10**17 eV, a maximum value of 3.2 at 3x10**17 eV, and a characteristic lightening above 3x10**17 eV up to 4x10**18 eV. All of these distinctive features are in accord with the data of many experiments. Two additional consequences intrinsic to the theory are qualitatively discussed: (1) some limitative bounds on the mechanism accelerating cosmic rays; (2) the degree of isotropy implied by the residence time of the cosmic rays in the Galaxy.
We have carried out a detailed study to understand the observed energy spectrum and composition of cosmic rays with energies up to ~10^18 eV. Our study shows that a single Galactic component with subsequent energy cut-offs in the individual spectra of different elements, optimised to explain the observed spectra below ~10^14 eV and the knee in the all-particle spectrum, cannot explain the observed all-particle spectrum above ~2x10^16 eV. We discuss two approaches for a second component of Galactic cosmic rays -- re-acceleration at a Galactic wind termination shock, and supernova explosions of …
We demonstrate that the UHECRs produced in the nuclear cascade in the jet of Low-Luminosity Gamma-Ray Bursts (LL-GRBs) can describe the UHECR spectrum and composition and, at the same time, the diffuse neutrino flux at the highest energies. The radiation density in the source simultaneously controls the neutrino production and the development of the nuclear cascade, leading to a flux of nucleons and light nuclei describing even the cosmic-ray ankle at $5 \times 10^{18}$ eV. The derived source parameters are consistent with population studies, indicating a baryonic loading factor of about ten. …
Cosmic rays around the knee are generally believed to be of galactic origin. Observations on their energy spectrum and chemical composition are important for understanding the acceleration and propagation of these cosmic rays. In addition, it is required to clarify the transition from galactic to extragalactic sources. In this paper, results of recent experiments measuring around the knee will be reviewed along with the detection techniques. The results on the all-particle energy spectrum and composition in the energy range of the knee up to the ankle will be discussed.
The origin and nature of the ultrahigh energy cosmic rays remains a mystery. However, considerable progress has been achieved in past years due to observations performed by the Pierre Auger Observatory and Telescope Array. Above $10^{18}$ eV the observed energy spectrum presents two features: a hardening of the slope at $\sim 10^{18.6}$ eV, which is known as the ankle, and a suppression at $\sim 10^{19.6}$ eV. The composition inferred from the experimental data, interpreted by using the current high energy hadronic interaction models, seems to be light below the ankle, showing a trend to heavi…
We have used recently published data from the Pierre Auger Observatory and the Telescope Array Project to conclude some inferences concerning the origin and composition of ultra high-energy cosmic rays (UHECR). We advocate for model the UHECR flux as a combination of the Galactic and Extragalactic components exchanging the dominant role at the famous feature of the energy spectrum called 'the ankle'. We put a special emphasis on the individual experiment energy resolution and possible biases it introduces. We have eventually combined the data from both big experiments to the one 'world average…
We study the anisotropies on large angular scales which can be present in the flux of cosmic rays reaching the Earth from a population of extragalactic sources, focusing on the energy range between the second knee and the ankle. In this energy range the particles are significantly affected by the Galactic magnetic field, which then plays a relevant role in shaping the expected anisotropies. The Galactic magnetic field deflects the cosmic-ray trajectories and thus modifies the anisotropies present outside the halo of the Galaxy, in particular the dipolar one associated with the translational mo…
We investigate non-thermal electron and nuclei energy losses within the binary neutron star merger remnant produced by the event GW170817. The lack of a cooling feature within the detected synchrotron emission from the source is used to constrain the magnetic field at the mG level, assuming that this emission is electron synchrotron in origin, and that the accelerated spectrum in the electrons follows the form $dN/dE_e \propto E_e^{-2}$. The level of subsequent gamma-ray emission from the source is demonstrated to provide a further constraint on the source magnetic field strength. We also put …
The cosmic ray flux measured by the Telescope Array Low Energy Extension (TALE) exhibits three spectral features: the knee, the dip in the $10^{16}$ eV decade, and the second knee. Here the spectrum has been measured for the first time using fluorescence telescopes, which provide a calorimetric, model-independent result. The spectrum appears to be a rigidity-dependent cutoff sequence, where the knee is made by the hydrogen and helium portions of the composition, the dip comes from the reduction in composition from helium to metals, the rise to the second knee occurs due to intermediate range n…
All information about primary cosmic rays above the knee has been obtained from results of EAS investigations. At that, two alternative approaches exist: cosmophysical and nuclear physical. In the frame of the first one, all changes in measured EAS characteristics are explained by the changes in energy spectrum and mass composition of primary cosmic rays. In this paper, the second approach is considered, in frame of which corresponding changes in EAS parameters are explained by changes of interaction model above the knee. Some experimental possibilities of proof of the correctness of the nucle…
The nature of the knee in the all-particle spectrum of cosmic rays remains subject of much investigation, especially in the aftermath of recent measurements claiming the detection of a knee-like feature in the spectrum of the light component of cosmic rays at energy $\sim$700 TeV, at odds with the standard picture in which the knee in the all-particle spectrum is dominated by light cosmic rays. Here we investigate the implications of this and other scenarios in terms of the measured flux of atmospheric neutrinos. In particular we discuss the possibility that the spectrum of atmospheric neutrin…
Data from the NUCLEON space observatory give a strong indication of the existence of a new universal cosmic ray "knee", which is observed in all groups of nuclei, including heavy nuclei, near a magnetic rigidity of about 10\,TV. Universality means the same position of the knee in the magnetic rigidity scale for all groups of nuclei. The knee is observed by both methods of measurement of particles energy implemented in the NUCLEON observatory---the calorimetric method and the kinematic method KLEM. This new cosmic ray "knee" is probably connected with the limit of acceleration of cosmic rays by…
Joint constraint on the propagation origin of the cosmic-ray spectral knee from energy spectrum and anisotropy observations
State Key Laboratory of Particle Astrophyics, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所粒子天体物理国家重点实验室）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；School of Physical Science and Technology, Southwest Jiaotong University（西南交通大学物理科学与技术学院）；TIANFU Cosmic Ray Research Center（天府宇宙线研究中心）
The possibility of estimating the mass composition of primary cosmic rays above the knee of its energy spectrum through the study of high energy gamma rays, muons and neutrinos produced in the interactions of cosmic rays with the solar ambient matter and radiation has been explored. It is found that the theoretical fluxes of TeV gamma rays, muons and neutrinos from a region around $15^{o}$ of the Sun are sensitive to mass composition of cosmic rays in the PeV energy range. The experimental prospects for detection of such TeV gamma rays/neutrinos by future experiments are discussed.
The cosmic-ray (CR) knee and the compositions contain abundant information for probing the CR's origin, acceleration and propagation mechanisms, as well as the frontier of the fundamental physics. Realizing that major proposals toward the knee's shape can be divided into two categories: the rigidity-dependent (also Z-dependent) knee and the mass-dependent (also A-dependent) knee, where the former one relates to the acceleration or the propagation mechanisms, and the other one is often associated with the new physics, it is essential to precisely measure the individual compositions. Benefit fro…
X-ray Binaries: a potential dominant contributor to the cosmic ray spectral knee structure
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Southwest Jiaotong University（西南交通大学）；Tangshan University（唐山学院）；TIANFU Cosmic Ray Research Center（天府宇宙线研究中心）
This article presents a description of a cosmic rays diffusive propagationmodel of a close point-like flash lamp like source and an approximation ofexperimentally observed spectral irregularity with this model. We show thatthis spectral irregularity can be explained using the presented model andprovide the most probable characteristics of such a source as well as severalobserved and identified sources which can be candidates for this role.
A Multi-messenger Search for a Nearby Microquasar Contributor to the Cosmic Ray Knee
School of Physical Science and Technology, Southwest Jiaotong University（西南交通大学物理科学与技术学院）；State Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所粒子天体物理国家重点实验室）；University of Chinese Academy of Sciences（中国科学院大学）；TIANFU Cosmic Ray Research Center（天府宇宙线研究中心）
The energy spectrum of the cosmic radiation in the range 10$^{19}$-2.4$\times$10$^{21}$ eV has been recently predicted showing a rich and distinctive staircase profile. In order to check the prediction, the spectra measured by running and past experiments above 10$^{19}$ eV are examined. The computed spectrum compares more favourably with the Telescope Array, HiRes I and Yakutsk data rather than with the Auger data in the range (1-20)$\times$10$^{19}$ eV. Previous flux measurements by Haverah Park, {\sc sugar}, {\sc agasa} and Fly's Eye experiments are above the predicted spectrum in the limit…
The Pierre Auger Observatory has recently reported the detection of a dipole anisotropy in the arrival directions of cosmic rays above 8 EeV with a post-trial significance of more than 5.2$σ$. This observation has profound consequences for the distribution and composition of candidate sources of cosmic rays above the ankle (3-5 EeV). In this paper we search for the presence of anisotropies on all angular scales in public Auger data. The analysis follows a likelihood-based reconstruction method that automatically accounts for variations in the observatory's angular acceptance and background rat…
Co-evolution of cosmic ray energy spectra, composition, and anisotropies
Deutsches Elektronen-Synchrotron (DESY)（德国电子同步辐射研究所）；Universität Potsdam（波茨坦大学）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；University of Science and Technology of China（中国科学技术大学）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）
The mixed Hydrogen and Helium (H + He) spectrum with a clear steepening at $\sim 700$ TeV has been detected by ARGO-YBJ experiments. In this paper, we demonstrate that the observed H + He spectrum can be well reproduced with the model of cosmic rays escaping from the supernova remnants (SNRs) in our Galaxy. In this model, particles are accelerated in a SNR through a non-linear diffusive shock acceleration mechanism and three components of high energy light nuclei escaped from the SNR are considered. It should be noted that the proton spectrum observed by KASCADE can be also explained by this m…
We perform a fit to measurements of the cosmic ray spectrum and of the depth of shower maximum in the energy range between $10^{15}$~eV and $10^{18}$~eV. We consider a Galactic component that is a mixture of five representative nuclear species (H, He, N, Si and Fe), for which we adopt rigidity dependent broken power-law spectra, and we allow for an extragalactic component which becomes strongly suppressed for decreasing energies. The relative abundances of the Galactic components at $10^{15}$~eV are taken to be comparable to those determined by direct measurements at $10^{13}$~eV. The main fea…
Nonmonotonic change with energy of the mean logarithmic mass of cosmic rays in the knee region: the mechanism of formation of this feature and sources of particles
Microquasar Remnants as Pevatrons Illuminating the Galactic Cosmic Ray Knee
Key Laboratory of Particle Astrophysics and Experimental Physics Division and Computing Center, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所粒子天体物理重点实验室及实验物理部计算中心）；TIANFU Cosmic Ray Research Center（天府宇宙线研究中心）；Department of Physics and Astronomy, University of Utah（犹他大学物理与天文系）
Spectral Softenings, Composition Bump, and Anisotropy Transition: A Consistent Picture of Cosmic-Ray Origin Below the Knee
Hebei Normal University（河北师范大学）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；University of Wisconsin–Madison（威斯康星大学麦迪逊分校）；TIANFU Cosmic Ray Research Center（天府宇宙线研究中心）；University of Chinese Academy of Sciences（中国科学院大学）
