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1.
In this paper we show that CP-violation is operating in most cosmic-ray sources such as black holes, active galactic nuclei, supernova remnants, and that this leads to the in-equality of the electron—positron component of cosmic rays.Further implications of this result are also discussed. 相似文献
2.
A. V. Uryson 《Astronomy Letters》2005,31(11):755-759
We estimate the detection rate of ultra-high-energy cosmic rays on ground-based arrays by assuming that the cosmic-ray sources are active galactic nuclei. We analyze the cases of detection of clusters, several particles that arrived, within the error limits, from the same area of the sky. The adopted model is shown to explain the detection rate of clusters on the AGASA array. 相似文献
3.
宇宙线的观测研究和暗物质粒子的间接探测是高能天体物理领域两个重大研究课题. 自1912年V. Hess发现宇宙线开始, 人类对宇宙线的观测历史已经超过了一个世纪, 传统理论模型预言``膝''区以下能段的宇宙线能谱应服从单一幂率分布, 而近些年的空间和高空气球实验表明10 GeV--100 TeV的宇宙线质子能谱可能存在偏离单一幂律谱分布的重要结构, 这对研究银河系内宇宙线的起源、传播和加速机制具有重要意义. 另一方面, 得益于宇宙线和伽马射线观测精度的提高和观测能段的拓宽, 暗物质粒子的间接探测在国际上受到越来越多的关注, 暗物质粒子可能会发生湮灭或衰变产生稳定的普通高能粒子, 包括正负电子对、正反质子对、伽马射线和中微子等, 进而在宇宙线或伽马射线留下可探测的信号. 相似文献
4.
We investigate the problem of transition from galactic cosmic rays to extragalactic ultra-high energy cosmic rays. Using the model for extragalactic ultra-high energy cosmic rays and observed all-particle cosmic ray spectrum, we calculate the galactic spectrum of iron nuclei in the energy range 108–109 GeV. The flux and spectrum predicted at lower energies agree well with the KASCADE data. The transition from galactic to extragalactic cosmic rays is distinctly seen in spectra of protons and iron nuclei, when they are measured separately. The shape of the predicted iron spectrum agrees with the Hall diffusion. 相似文献
5.
From our recent observations of the charge and energy spectra of cosmic-ray nuclei we have constructed secondary-to-primary charge ratios at the two ends of the charge spectrum. These ratios are found to be inconsistent with thead hoc leaky-box model of cosmic-ray propagation which leads to an exponential pathlength distribution. Models for which the pathlength distribution function is deficient in short pathlengths provide a more consistent picture. Several of these models are investigated, bothad hoc and physical. The physical model considered here is one for which detailed galactic propagation parameters and boundary conditions are used and for which there exists no near sources of cosmic rays over a time interval corresponding to a few times the cosmic-ray age. 相似文献
6.
E. N. Parker 《Astrophysics and Space Science》1973,24(1):279-288
The origin and behavior of cosmic rays in the Galaxy depends crucially upon whether the galactic magnetic field has a closed topology, as does the field of Earth, or whether a major fraction of the lines of force connect into extragalactic space. If the latter, then cosmic rays could be of extragalactic origin, or they could be of galactic origin, detained in the Galaxy by the scattering offered by hydromagnetic waves, etc. If, on the other hand, the field is largely closed, then cosmic rays cannot be of extragalactic origin (at least below 1016 eV). They must be of galactic origin and escape because their collective pressure inflates the galactic field and they push their way out.This paper examines the structure of a galactic field that opens initially into intergalactic space and, with the inclusion of turbulent diffusion, finds no possibility for maintaining a significant magnetic connection with an extragalactic field. Unless some mechanism can be found, we are forced to the conclusion that the field is closed, that cosmic rays are of galactic origin, and that cosmic rays escape from the Galaxy only by pushing their way out. 相似文献
7.
宇宙线的起源是高能天体物理的核心问题之一.一直以来,超新星爆发被认为是能谱膝区以下宇宙线的主要来源.多波段观测表明,超新星遗迹有能力加速带电粒子至亚PeV (10~(15)eV)能量.扩散激波加速被认为是最有效的天体高能粒子加速机制之一,而超新星遗迹的大尺度激波正好为这一机制提供平台.近年来,一系列较高精度的地面和空间实验极大地推动了对宇宙线以及超新星遗迹的研究.新的观测事实挑战着传统的扩散激波加速模型以及其在银河系宇宙线超新星遗迹起源学说上的应用,深化了人们对宇宙高能现象的认识.结合超新星遗迹辐射能谱的时间演化特性,构建的时间依赖的超新星遗迹粒子加速模型,不仅能够解释200 GV附近宇宙线的能谱反常,还自然地形成能谱膝区,甚至可以将超新星遗迹粒子加速对宇宙线能谱的贡献延伸至踝区.该模型预期超新星遗迹中粒子的输运行为表现为湍流扩散,这需要未来的观测以及与粒子输运相关的等离子体数值模拟工作来进一步验证. 相似文献
8.
Wolfgang Kundt 《Astrophysics and Space Science》1992,195(2):331-340
It is argued that most of the volume of the galactic disk is filled with cosmic rays, whereby electrons and positrons contribute significantly to the pressure (and energy) balance. The pair plasma and the cosmic rays escape into the halo through the galactic chimmeys which have their origins in strong Hii regions. The most conspicuous phenomena in the halo are caused by the jets from the (intermittently active) nucleus whose channel walls serve as cold traps. 相似文献
9.
The propagation of radioactive nuclei of cosmic rays in a flat diffusion galactic model (sources and the main gaseous mass are concentrated in the galactic disc) is considered. The corresponding results are not reducible to the results of a simple homogeneous model. It is shown that the recent data on the Be10 nuclei abundance in cosmic rays do not contradict the occurrence of a large cosmic ray halo. 相似文献
10.
C. Grimani 《Astrophysics and Space Science》1999,268(4):475-481
Quest for antimatter in cosmic rays has revealed no compelling evidence of primary, extragalactic antiparticles up to the
present time. Recent positron and antiproton observations have been found to be consistent with a pure galactic origin up
to energies of 50 GeV and 20 GeV respectively. In this paper it is discussed which role might be played by Ultra High Energy
(UHE) extragalactic particles and antiparticles in cosmic-ray observations near Earth.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
12.
We have examined the characteristics of the unusual worldwide fluctuations of cosmic-ray intensity on July 14–15, 1961, using corrected hourly data from global network of neutron and meson detectors. A careful study of the associated solar, interplanetary and geophysical phenomena has also been made. These investigations lead us to recognise the dominant role played by the Interplanetary Magnetic Field Inhomogeneities (IMFI) in modulating galactic cosmic-ray flux received at earth during recovery from Forbush decreases. When approaching the earth from the sunward side the IMFI's scatter galactic cosmic rays diffusing towards solar equatorial plane from higher heliolatitudes on to the interplanetary magnetic-field lines which connect to earth. When propagating past the orbit of the earth, the IMFI's set up a flow of scattered galactic cosmic-ray flux in the general direction of the earth. Most of these cosmic rays probably sink in the sun. Transient Spatial Anisotropies are thus set up in the vicinity of the earth in cosmic-ray intensity as viewed by ground-based detectors. Depending upon the relative position of the region abounding in IMFI's and the earth, these short-lived anisotropies appear either from sunward or antisun directions. Sometimes the configuration is such as to set up bidirectional anisotropies. Implications of this broad picture are discussed qualitatively.Our analysis also enables us to place constraint on the mechanism responsible for heating the solar corona over active regions, which we feel must be taken into account by all theoretical models on the subject.This research is supported in part by U.S. Air Force Office of Scientific Research under grant AF-AFOSR-319-66. The paper was presented at the Tenth International Conference on Cosmic Rays, Calgary, June 18–29, 1967.Now at the Dept. of Physics and Astronomy, University of New Mexico, Albuquerque, N.M., U.S.A. 相似文献
13.
We study the impact of possible spiral-arm distributions of Galactic cosmic-ray sources on the flux of various cosmic-ray nuclei throughout our Galaxy. We investigate model cosmic-ray spectra at the nominal position of the sun and at different positions within the Galaxy. The modelling is performed using the recently introduced numerical cosmic ray propagation code Picard. Assuming non-axisymmetric cosmic-ray source distributions yields new insights on the behaviour of primary versus secondary nuclei.We find that primary cosmic rays are more strongly confined to the vicinity of the sources, while the distribution of secondary cosmic rays is much more homogeneous compared to the primaries. This leads to stronger spatial variation in secondary to primary ratios when compared to axisymmetric source distribution models. A good fit to the cosmic-ray data at Earth can be accomplished in different spiral-arm models, although leading to decisively different spatial distributions of the cosmic-ray flux. These lead to different cosmic ray anisotropies, where even reproducing the data becomes possible. Consequently, we advocate directions to seek best fit propagation parameters that take into account the higher complexity introduced by the spiral-arm structure on the cosmic-ray distribution. We specifically investigate whether the flux at Earth is representative for a large fraction of the Galaxy. The variance among possible spiral-arm models allows us to quantify the spatial variation of the cosmic-ray flux within the Galaxy in presence of non-axisymmetric source distributions. 相似文献
14.
A. J. Owens 《Astrophysics and Space Science》1976,40(2):357-367
The general solution for the distribution of ages for primary galactic cosmic rays is given for a class of steady-state, bounded models of cosmic-ray diffusion in the Galaxy. Both one-and threedimensional models are considered, with point sources and distributed sources. In all models, the age distribution, is approximately exponential for ages longer than the average age, although for shorter ages the distribution depends on the details of the model. The leaky-box model, with an exponential age distribution, is thus a good approximation to most diffusive models. It is shown that one-dimensional (disk) models are consistent with both age and anisotropy data for galactic cosmic rays regardless of whether production takes place near the galactic center or throughout the disk. 相似文献
15.
Micha&#; Ostrowski 《Monthly notices of the Royal Astronomical Society》2000,312(3):579-584
We consider effects on an (ultra)relativistic jet and its ambient medium caused by high-energy cosmic rays accelerated at the jet side boundary. As illustrated by simple models, during the acceleration process a flat cosmic ray distribution can be created, with gyro-radii for the highest particle energies reaching scales comparable to the jet radius or energy density comparable to the pressure of the ambient medium . In the case of efficient radiative losses, a high-energy bump in the spectrum can dominate the cosmic ray pressure. In extreme cases, the cosmic rays are able to push the ambient medium off, providing a 'cosmic ray cocoon' separating the jet from the surrounding medium. The considered cosmic rays provide an additional jet braking force and lead to a number of consequences for the jet structure and its radiative output. In particular, the dynamic and acceleration time-scales involved are in the range observed in variable active galactic nuclei. 相似文献
16.
A. V. Uryson 《Astronomy Letters》2017,43(8):529-535
We provide our estimates of the intensity of the gamma-ray emission with an energy near 0.1 TeV generated in intergalactic space in the interactions of cosmic rays with background emissions. We assume that the cosmic-ray sources are pointlike and that these are active galactic nuclei. The following possible types of sources are considered: remote and powerful ones, at redshifts up to z = 1.1, with a monoenergetic particle spectrum, E = 1021 eV; the same objects, but with a power-law particle spectrum; and nearby sources at redshifts 0 < z ≤ 0.0092, i.e., at distances no larger than 50 Mpc also with a power-law particle spectrum. The contribution of cosmic rays to the extragalactic diffuse gammaray background at an energy of 0.1 TeVhas been found to depend on the type of sources or, more specifically, the contribution ranges from f ? 10?4 to f ≈ 0.1, depending on the source model. We conclude that the data on the extragalactic background gamma-ray emission can be used to determine the characteristics of extragalactic cosmic-ray sources, i.e., their distances and the pattern of the particle energy spectrum. 相似文献
17.
《Chinese Astronomy and Astrophysics》2020,44(1):1-31
The origin of cosmic rays is one of the key questions in high-energy astrophysics. Supernovae have been always considered as the dominant sources of cosmic rays below the energy spectrum knee. Multi-wavelength observations indeed show that supernova remnants are capable for accelerating particles into sub-PeV (10 eV) energies. Diffusive shock acceleration is considered as one of the most efficient acceleration mechanisms of astrophysical high-energy particles, which may just operate effectively in the large-scale shocks of supernova remnants. Recently, a series of high-precision ground and space experiments have greatly promoted the study of cosmic rays and supernova remnants. New observational features challenge the classical acceleration model by diffusive shock and the application to the scenario of supernova remnants for the origin of Galactic cosmic rays, and have deepened our understanding to the cosmic high-energy phenomena. In combination with the time evolution of radiation energy spectrum of supernova remnants, a time-dependent particle acceleration model is established, which can not only explain the anomalies in cosmic-ray distributions around 200 GV, but also naturally form the cosmic-ray spectrum knee, even extend the contribution of supernova particle acceleration to cosmic ray flux up to the spectrum ankle. This model predicts that the high-energy particle transport behavior is dominated by the turbulent convection, which needs to be verified by future observations and plasma numerical simulations relevant to the particle transport. 相似文献
18.
Ajoy K. Dasgupta 《Astrophysics and Space Science》1983,96(2):333-342
Cosmic rays of interest here are electrically charged protons or nuclei having kinetic energy of the order of 1018 eV or more. The theory of cosmic-ray propagation is carried out on the assumption that the original particle may be of extragalactic origin. The curvature and gradient drift is incorporated in the anti-symmetric term of the diffusion tensor. The theory of force-field is examined including diffusion, convection, and energy losses of the cosmic rays. Finally some observation aspects are included in the concluding remarks. 相似文献
19.
G. F. Krymsky P. A. Krivoshapkin S. K. Gerasimova P. Yu. Gololobov 《Astronomy Letters》2014,40(4):230-233
Long-termobservations of the muon intensity of galactic cosmic rays at the Nagoya (35°10′ N, 136°58′ E) and Yakutsk (62°01′ N, 129°43′ E) stations have revealed amplitude-phase annual and semiannual oscillations of the semidiurnal variation. These oscillations are attributable to the properties of the cosmic-ray anisotropy tensor that result from shielding by the interplanetary magnetic field and solar-wind shear flow. The mentioned tensor is also shown to have a north-south asymmetry. 相似文献
20.
A. P. Trofimenko 《Astrophysics and Space Science》1989,159(2):301-315
Astrophysical applications of white and grey holes are considered. Four types of anticollapsars in extended manifolds of general relativity are distinguished: canonical white and grey holes, light- and dark-grey holes. White and grey holes can be revealed in the form of bursts of gravitational and electromagnetic radiation, neutrino, and cosmic rays. Quasars, active galactic nuclei, jets, and cosmic voids can be associated with relicts of white and light-grey holes, and black holes do with relicts of canonical grey and dark-grey holes. 相似文献