Tamar Kashti
We briefly summarize our study on anisotropy of Ultra-High Energy Cosmic-Rays (UHECRs), in which we define a statistics that measures the correlation between UHECRs and Large Scale Structure (LSS). We also comment here on recently published paper by Koers and Tinyakov that compared our statistics to improved KS statistics.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
继续探索
The arrival directions of Galactic cosmic rays exhibit anisotropies up to the level of one per-mille over various angular scales. Recent observations of TeV-PeV cosmic rays show that the dipole anisotropy has a strong energy dependence with a phase-flip around 100 TeV. We argue that this behavior can be well understood by the combination of various effects: the anisotropic diffusion of cosmic rays, the presence of nearby sources, the Compton-Getting effect from our relative motion and the reconstruction bias of ground-based observatories.
Searches for dark matter annihilation signals in the diffuse gamma-ray background are promising. We present the first comprehensive study utilizing both flux and anisotropy, using the example of a spectral line signal. Besides improving sensitivity, a combined analysis will help separately determine the particle properties of dark matter and the cosmological aspects of its clumping into halo substructure. The significance of a signal in a shot-noise-dominated anisotropy analysis increases linearly with time $t$, as opposed to $\sqrt{t}$ for a flux analysis, so a flux hint might be confirmed wi…
Recent measurements of the dipole anisotropy in the arrival directions of Galactic cosmic rays (CRs) indicate a strong energy dependence of the dipole amplitude and phase in the TeV-PeV range. We argue here that these observations can be well understood within standard diffusion theory as a combined effect of (i) one or more local sources at Galactic longitude 120deg < l < 300deg dominating the CR gradient below 0.1-0.3 PeV, (ii) the presence of a strong ordered magnetic field in our local environment, (iii) the relative motion of the solar system, and (iv) the limited reconstruction capabilit…
The High-Altitude Water Cherenkov (HAWC) Observatory, located 4100 m above sea level near Sierra Negra (19$^\circ$ N) in Mexico, is sensitive to gamma rays and cosmic rays at TeV energies. The arrival direction distribution of cosmic rays at these energies shows significant anisotropy on several angular scales, with a relative intensity ranging between 10$^{-3}$ and 10$^{-4}$. We present the results of a study of cosmic-ray anisotropy based on more than 86 billion cosmic-ray air showers recorded with HAWC since June 2013. The HAWC cosmic-ray sky map, which has a median energy of 2 TeV, exhibit…
We study the anisotropy in the arrival directions of PAO UHECRs, using the point source correlational angular distance distribution. The result shows that the anisotropy is characterized by one prominent excess region and one void region. The excess region is located near the Centaurus A direction, supporting that the Centaurus A is a promising UHECR source. The void region near the south pole direction may be used to limit the diffuse isotropic background contribution.
Recent results of Milagro, Tibet, ARGO-YBJ and IceCube experiments on the small-scale anisotropy of Galactic cosmic rays (CRs) with energies from units up to a few hundred TeV arise a question on a possible nature of the observed phenomenon, as well as on the anisotropy of CRs at higher energies. An analysis of a small-scale anisotropy of CRs with energies at around PeV registered with the EAS MSU array presented in the article, reveals a number of regions with an excessive flux. A typical size of the regions varies from 3 up to 12 degrees. We study correlation of these regions with positions …
The IceCube Neutrino Observatory is a kilometer-scale detector currently under construction at the South Pole. In its final configuration the detector will comprise 5160 Digital Optical Modules (DOMs) deployed on 86 strings between 1.5-2.5 km deep within the ice. While still incomplete, the detector has already recorded tens of billions of cosmic ray muons with a median energy of 20 TeV. This large sample has been used to study the arrival direction distribution of the cosmic rays. We report the observation of an anisotropy in the cosmic rays arrival direction at two different angular scales. …
The interaction of high energy cosmic rays with the Earth's atmosphere produces extensive air showers of secondary particles with a large muon component. By exploiting the sensitivity of neutrino telescopes to high energy muons, it is possible to use these detectors for precision cosmic ray studies. The high rate of cosmic-ray muon events provides a high-statistics data sample that can be used to look for anisotropy in the arrival directions of the parent particles at the per-mille level. This paper reports on the observation of anisotropy in the cosmic ray data collected with the IceCube neut…
We investigate the neutrino - cosmic ray connection for sources in the Galaxy in terms of two observables: the shape of the energy spectrum and the distribution of arrival directions. We also study the associated gamma ray emission from these sources.
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 …
A search for anisotropy at different scales in the arrival directions of cosmic rays with energies above 1 PeV is performed with data of the Tunka-133 array. A number of regions with angular sizes up to approximately 30 degrees that deviate from the uniform background with a statistical significance greater than three standard deviations are found using the shuffling technique both in the complete data set and its subsets in different energy ranges. Some regions with an excess of cosmic rays correlate with the distribution of possible cosmic ray sources. A comparison of the results with a simi…
We present results of elaborate four-dimensional simulations of the propagation of ultra-high-energy cosmic rays (UHECR), which are based on a realistic astrophysical scenario. The distribution of the arrival directions of the UHECR is found to have a pronounced dipolar anisotropy and rather weak higher-order contributions to the angular power spectrum. This finding agrees well with the recent observation of a dipolar anisotropy for UHECR with arrival energies above 8 EeV by the Pierre Auger Observatory and constitutes an important prediction for other energy ranges and higher-order angular co…
Results are presented that were obtained by analysing the arrival directions of E0 > 8x10**18 eV primary cosmic rays recorded at the Yakutsk array over the period between 1974 and 2003 and at the SUGAR array (Australia). The greatest primary cosmic ray flux is shown to arrive from the region of visible intersection of the planes of the Galaxy and the Supergalaxy (local supercluster of galaxies) at a galactic longitude of about 137 degres. On a global scale, the lowest temperature of the cosmic microwave background is typical of this region.
A thorough search for large scale anisotropies in the distribution of arrival directions of cosmic rays detected above $10^{18}$ eV at the Pierre Auger Observatory is reported. For the first time, these large scale anisotropy searches are performed as a function of both the right ascension and the declination and expressed in terms of dipole and quadrupole moments. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Upper limits on dipole and quadrupole amplitudes are derived under the hypothesis that any cosmic ray anisotropy is dominated by such moments i…
We examine the role of the large--scale anisotropy of the high--energy cosmic ray distribution in a search for the heavy decaying dark matter (DM) signal. Using recent anisotropy measurements from the extensive air shower (EAS) observatories we constrain the lifetime of the DM particles with masses $10^{7}~\leq~M_X~\leq~10^{16}$ GeV. These constraints appear to be weaker than that obtained with the high energy gamma-ray limits. We also estimate the desired precision level for the anisotropy measurements to discern the decaying DM signal marginally allowed by the gamma-ray limits and discuss th…
Several experiments have reported regions in the TeV sky with an excess of cosmic rays. Here we consider the possibility that the excess cosmic rays are coming from dark matter annihilation in nearby subhalos. We provide motivation for dark matter as the source of the excess and show that dark matter annihilations can naturally produce the cosmic ray anisotropy without the need for exotic dark matter models. We show that viable dark matter explanations of the cosmic ray excess are consistent with current measurements of antiprotons, positrons, and gamma-rays. Additionally, we show that the dar…
Between May 2009 and May 2010, the IceCube neutrino detector recorded 32 billion of atmospheric muons generated in air showers produced by cosmic rays in the TeV energy range. With such high statistics sample it is possible to observe, for the first time in the southern hemisphere, an energy dependence in the Galactic cosmic ray anisotropy up to a few hundred TeV. This study shows that the same large-scale anisotropy observed at median energies around 20 TeV is not present at 400 TeV; the anisotropy observed at 400 TeV shows substantial differences with respect to that at lower energy. In addi…
Three dimensional (3D) galactic cosmic ray (GCR) anisotropy has been studied for 2006- 2012. The GCR anisotropy, both in the ecliptic plane and in polar direction, were obtained based on the neutron monitors (NMs) and Nagoya muon telescopes (MT) data. We analyze two dimensional (2D) GCR anisotropy in the ecliptic plane and north-south anisotropy normal to the ecliptic plane. We reveal quasi-periodicities - the annual and 27-days waves in the GCR anisotropy in 2006-2012. We investigate the relationship of the 27-day variation of the GCR anisotropy in the ecliptic plane and in the polar directio…
Investigating Energy-Dependent Anisotropy in Cosmic Rays with IceTop Surface Array
本研究利用2011-2022年IceTop表面阵列数据，结合提升的统计精度与更新的模拟，将南半球宇宙线各向异性测量拓展至更高能段，为探索其与能谱、质量组成的关联奠定基础。
Large-scale anisotropy of Galactic cosmic rays as a probe of local cosmic-ray propagation
本文通过构建统一图景研究银河宇宙线大尺度各向异性，发现局域规则磁场和各向异性扩散可解释100 TeV以下偶极相位，并指出100 TeV以上相位依赖局域扩散演化，呼吁开展更精确测量以揭示局域传播和湍流。
Auger Collaboration has reported a large-scale anisotropy in the arrival directions of cosmic rays above 8 EeV. The dipole direction, at 125$^\circ$ from the Galactic center, is taken as an indication of an extragalactic origin of these cosmic rays. We show, both theoretically and by direct numerical simulations, that this is not necessarily true. Intermediate mass nuclei originating in the Galaxy and diffusing in the Galactic magnetic field can have a dipole anisotropy pointing away from the Galactic center. Our theory predicts a quadrupole anisotropy of the same order of magnitude as the dip…
The Pierre Auger Collaboration discovered, in a solid angle of radius about 18\degree, a local group of cosmic rays having energies in the region E0 \geq 5.5\times1019 eV and coming from the region of the Gen A radio galaxy, whose galactic coordinates are lG = 309.5\degree and bG = 19.4\degree. Near it, there is the Centaur supercluster of galaxies, its galactic coordinates being lG = 302.4\degree and bG = 21.6\degree. It is noteworthy that the Great Attractor, which may have a direct bearing on the observed picture, is also there.
Cosmic rays in the energy range from about 10's GeV to several 100's TeV are observed on Earth with an energy-dependent anisotropy of order 0.01-0.1%, and a consistent topology that appears to significantly change at higher energy. The nearest and most recent galactic cosmic ray sources might stochastically dominate the observation and possibly explain a change in orientation of the anisotropy as a function of energy. However, the diffusion approximation is not able to explain its non-dipolar structure and, in particular, the significant contribution of small angular scale features. Particle p…
In this letter, we present an update of a method for analysing arrival directions of ultra-high-energy cosmic rays (UHECRs) above the Greisen--Zatsepin--Kuz'min cut-off with a deep convolutional neural network developed originally in Kalashev, Pshirkov, Zotov (2020). Namely, we introduce energy as another variable employed in the analysis. This allows us to take into account the intrinsic uncertainties in energy of primary cosmic rays present in any experiment, which were not taken into account in the previous study, without any loss of quality of the classifier. We present the architecture of…
We will review the main physical aspects of Ultra High Energy Cosmic Rays. We will discuss in particular their propagation through astrophysical backgrounds, focusing on the latest experimental observations of HiRes, Telescope Array and Auger. We will also review the issue of the transition between galactic and extra-galactic cosmic rays.
If ultra-high-energy cosmic rays originate from extragalactic sources, the offsets of their arrival directions from these sources imply an upper limit on the strength of the extragalactic magnetic field. The Pierre Auger Collaboration has recently reported that anisotropy in the arrival directions of cosmic rays is correlated with several types of extragalactic objects. If these cosmic rays originate from these objects, they imply a limit on the extragalactic magnetic field strength of B < 0.7-2.2 x 10^-9 (lambda_B / 1 Mpc)^-1/2 G for coherence lengths lambda_B < 100 Mpc and B < 0.7-2.2 x 10^-…
We constrain the energy at which the transition from Galactic to extragalactic cosmic rays occurs by computing the anisotropy at Earth of cosmic rays emitted by Galactic sources. Since the diffusion approximation starts to loose its validity for E/Z >~ 10^(16-17) eV, we propagate individual cosmic rays (CRs) using Galactic magnetic field models and taking into account both their regular and turbulent components. The turbulent field is generated on a nested grid which allows spatial resolution down to fractions of a parsec. Assuming sufficiently frequent Galactic CR sources, the dipole amplitud…
We discuss the basic features of the propagation of Ultra High Energy Cosmic Rays in astrophysical backgrounds, comparing two alternative computation schemes to compute the expected fluxes. We also discuss the issue of the transition among galactic and extra-galactic cosmic rays using theoretical results on fluxes to compare different models.
Analysing Ultra High Energy Cosmic Rays' Anisotropy in $\boldsymbol{f(R, T)}$ Gravity Theory
本文通过参数化磁场与源距离，比较两个 $f(R,T)$ 引力模型和 $Λ$CDM 模型对 UHECRs 扩散各向异性的拟合，发现 $f(R,T)$ 模型给出更低振幅、更高各向同性。
The joint analysis of anisotropy signals and chemical composition of ultra-high energy cosmic rays offers strong potential for shedding light on the sources of these particles. Following up on an earlier idea, this paper studies the anisotropies produced by protons of energy >E/Z, assuming that anisotropies at energy >E have been produced by nuclei of charge Z, which share the same magnetic rigidity. We calculate the number of secondary protons produced through photodisintegration of the primary heavy nuclei. Making the extreme assumption that the source does not inject any proton, we find tha…
We investigate the effects of stochasticity in the spatial and temporal distribution of supernova remnants on the anisotropy of cosmic rays observed at Earth. The calculations are carried out for different choices of the diffusion coefficient D(E) for propagation in the Galaxy. The propagation and spallation of nuclei are taken into account. At high energies we assume that $D(E)\sim(E/Z)^δ$, with $δ=1/3$ and $δ=0.6$ being the reference scenarios. The large scale distribution of supernova remnants in the Galaxy is modeled following the distribution of pulsars with and without accounting for the…
The Compton-Getting origin of the large-scale anisotropy of Galactic cosmic rays
研究探讨了Compton-Getting效应如何影响银河宇宙射线的大尺度各向异性，并通过实验数据验证了该效应的存在与影响。
KLYPVE-EUSO (K-EUSO) is a planned orbital detector of ultra-high-energy cosmic rays (UHECRs), which is to be deployed on board the International Space Station. K-EUSO is expected to have a uniform exposure over the celestial sphere and register from 120 to 500 UHECRs at energies above 57 EeV in a 2-year mission. We employed the TransportCR and CRPropa 3 packages to estimate prospects of detecting a large-scale anisotropy of ultra-high-energy cosmic rays from a nearby source with K-EUSO. Nearby active galactic nuclei Centaurus A, M82, NGC 253, M87 and Fornax A were considered as possible source…
Observations of cosmic ray arrival directions made with the Pierre Auger Observatory have previously provided evidence of anisotropy at the 99% CL using the correlation of ultra high energy cosmic rays (UHECRs) with objects drawn from the Veron-Cetty Veron catalog. In this paper we report on the use of three catalog independent methods to search for anisotropy. The 2pt-L, 2pt+ and 3pt methods, each giving a different measure of self-clustering in arrival directions, were tested on mock cosmic ray data sets to study the impacts of sample size and magnetic smearing on their results, accounting f…
We discuss the possibility that some recently measured anisotropic cosmic ray components in the TeV-PeV energy range may be an indication of the ejection of a peculiar type of matter. We present a model where a neutron star internal transition with nuclear deconfinement of the quark content takes place. This catastrophic event may cause a mass ejection process seeding the insterstelar medium with droplets of quark matter, so called nuclearites. Neutralization of these droplets in molecular clouds may drive the anisotropy since quasi-rectilinear trajectories are allowed. Complementary informati…
Ultrahigh energy cosmic rays and neutrino flux models
本文综述超高能中微子搜索及其与宇宙线的关联，梳理产生机制、潜在源、模型无关通量基准及模型依赖预测方法。
Recent results from the Pierre Auger Observatory show energy dependent chemical composition of ultrahigh-energy cosmic rays (UHECR) with a growing fraction of heavy elements at high energies. This points to a non-negligible contribution of the Galactic sources, such as past GRBs and other rare but powerful stellar explosions in the Milky Way. The effects of diffusion in the Galactic magnetic fields alter the observed composition and render the flux of UHECR isotropic, up to a few per cent anisotropy in the direction of the Galactic Center, as well as some small-scale anisotropy with "hot spots…
The propagation of ultra-high energy cosmic rays in extragalactic magnetic fields can be diffusive, depending on the strength and properties of the fields. In some cases the propagation time of the particles can be comparable to the age of the universe, causing a suppression in the flux measured on Earth. In this work we use magnetic field distributions from cosmological simulations to assess the existence of a magnetic horizon at energies around 10$^{18}$ eV.
Ultra High Energy Cosmic Rays from the Local Void
研究通过本地虚空方向的超高能宇宙射线推测其可能为轻量磁单极子，并提出通过全天空观测确定其在10^20 eV以上的比例。
The large-scale anisotropy and flux (de-)magnification of ultra-high-energy cosmic rays in the Galactic magnetic field
本研究利用新银河系磁场模型计算UHECR到达方向，发现偶极分量降低源于河外通量峰值与去放大边界重合，为探测源分布和磁场提供新工具。
The PeV gamma ray background produced in the interactions of ultra high energy cosmic rays with the ambient matter and radiations during their propagation in the Milky Way has been calculated in this paper. If the primary ultra high energy cosmic rays are produced from Galactic point sources then those point sources are also emitting PeV gamma rays. We discuss that the detection of galactocentric PeV gamma rays in the future would be a signature of the presence of EeV cosmic accelerators in the Milky Way.
We study anisotropy of cosmic rays in the energy range 0.2-1.4 EeV at intermediate angular scales using the public data set of the Pierre Auger Observatory. At certain scales, the analysis reveals a number of deviations from the isotropic distribution with the statistical significance above three standard deviations. It also demonstrates that the anisotropy evolves with energy. If confirmed with the complete Auger or Telescope Array data sets, the result can shed new light on the structure of galactic magnetic fields and the problem of transition from galactic to extragalactic cosmic rays.
We argue that ultra-high energy cosmic rays emitted by galaxy clusters result in electric currents in filaments of the large-scale structure that are sufficient to generate magnetic fields in voids of the magnitude of ~1e-12 G and the coherence length of up to tens of Mpc. These fields satisfy both the lower and upper observational bounds on magnetic fields in voids without a need of any primordial component.
High energy electrons and positrons from annihilating dark matter can imprint unique angular anisotropies on the diffuse gamma-ray flux by inverse Compton scattering off the interstellar radiation field. We develop a numerical tool to compute gamma-ray emission from such electrons and positrons produced in the smooth host halo and in substructure halos with masses down to 10^(-6)M_sun. We show that the angular power spectrum from inverse Compton scattering is exponentially suppressed below an angular scale determined by the diffusion length of electrons and positrons. We also find that the tot…
The status of the observations of Ultra High Energy Cosmic Rays will be reviewed, focusing on the the latest results of HiRes and Auger observatories. A comprehensive analytical computation scheme to compute the expected UHECR spectrum on earth will be presented, applying such scheme to interpret the experimental results. The phenomenological scenarios favored by HiRes and Auger in terms of chemical composition and spectrum will be also presented.
Ultra high energy cosmic ray events presently show a spectrum, which we interpret here as galactic cosmic rays due to a starburst in the radio galaxy Cen A pushed up in energy by the shock of a relativistic jet. The knee feature and the particles with energy immediately higher in galactic cosmic rays then turn into the bulk of ultra high energy cosmic rays. This entails that all ultra high energy cosmic rays are heavy nuclei. This picture is viable if the majority of the observed ultra high energy events come from the radio galaxy Cen A, and are scattered by intergalactic magnetic fields acros…
Anisotropies of Diffusive Ultra-high Energy Cosmic Rays in $f(R)$ Gravity Theory
本研究在三种宇宙学模型下研究扩散超高能宇宙射线的偶极各向异性，发现 $f(R)$ 幂律模型预测幅度最大，$\Lambda$CDM 最小，为宇宙学与高能天体物理交叉研究提供新途径。
We review the main experimental evidences on ultra high energy cosmic rays and their implications in the physics of these extremely energetic particles, also in connection with dark matter and cosmology. We discuss the basis of theoretical models aiming at explaining observations, highlighting the most relevant open questions in this fascinating field of research.
The observation of neutrinos from cosmic accelerators will be revolutionary. High energy neutrinos are closely connected to ultrahigh energy cosmic rays and their sources. Cosmic ray sources are likely to produce neutrinos and the propagation of ultrahigh cosmic rays from distant sources can generate PeV to ZeV neutrinos. We briefly review recent progress on the observations of ultrahigh energy cosmic rays and their implications for the future detections of high energy neutrinos.
Revisiting the implications of Liouville's theorem to the anisotropy of cosmic rays
本文通过球谐函数展开求解刘维尔方程，探讨宇宙射线到达方向分布的解释，发现初始各向同性通量保持各向同性需满足源的各向同性和均匀性，分析了磁偶极子的形成与消失条件，并预测四极子信号的观测能量范围。
The study of ultra-high energy cosmic rays (UHECRs) has recently experienced a jump in statistics as well as improved instrumentation. This has allowed a better sensitivity in searching for anisotropies in the arrival directions of cosmic rays. In this written version of the presentation given by the inter-collaborative "Anisotropy Working Group" at the International Symposium on Future Directions in UHECR physics at CERN in February 2012, we report on the current status for anisotropy searches in the arrival directions of UHECRs.
As cosmic rays (CRs) propagate in the Galaxy, they can be affected by magnetic structures that temporarily trap them and cause their trajectories to display chaotic behavior, therefore modifying the simple diffusion scenario. When CRs arrive at the Earth, they do so anisotropically. These chaotic effects can be a fundamental contributor to this anisotropy. Accordingly, this requires a comprehensive description of chaos in trapping conditions since assessing their repercussions on the CR arrival directions is necessary. This study utilizes a new method described in López-Barquero and Desiati (2…
It has been shown that supernova blast waves interacting with winds from massive stars in compact star clusters may be capable of producing cosmic-ray (CR) protons to above $10^{17}$ eV. We give a brief description of the colliding-shock-flows mechanism and look at generalizations of the diffusion of ~ 100 PeV CRs in the turbulent galactic magnetic field present in the galactic disk. We calculate the temporal evolution of the CR anisotropy from a possible distribution of young compact massive star clusters assuming the sources are intermittent on time scales of a few million years, i.e., compa…
We briefly review the main channels of gamma ray and neutrino production due to the propagation of ultra high energy cosmic rays. We show how the observations of these secondary radiations are of paramount importance in tagging mass composition and sources of ultra high energy cosmic rays.
Recently studies of the dipole anisotropy in the arrival directions of Galactic cosmic rays indicate that the TeV-PeV dipole anisotropy amplitude is not described by a simple power law, moreover a rapid phase change exists at an energy of $0.1\sim0.3$ PeV. In this work we argue that the dipole anisotropy amplitude and phase evolution with energies can be reproduced under the spatially-dependent propagation scenario with a nearby single source added. Our results indicate a nearby single source have significant influence to the cosmic ray gradient below $0.1\sim0.3$ PeV under the spatially-depen…
It is suggested that essentially all of the UHECRs we detect, including those at the highest energy, originate in our Galaxy. It is shown that even if the density of sources decreases with Galactic radius, then the anisotropy and composition can be understood. Inward anisotropy, as recently reported by the Auger collaboration can be understood as drift along the current sheet of UHECRs originating outside the solar circle, as predicted in Kumar and Eichler (2014), while those originating within the solar circle exit the Galaxy at high latitudes.
We search for anisotropies in the arrival directions of cosmic rays observed by the KASCADE-Grande air shower experiment. The analysis is based on public data of about 23.7 million events with reconstructed primary energies above 1 PeV. We apply a novel maximum-likelihood reconstruction method for the cosmic ray anisotropy, that compensates for spurious anisotropies induced by local detector effects. We find no evidence for a large-scale dipole anisotropy in the data, consistent with official results based on the conventional East-West derivative method. On the other hand, a subset of cosmic r…
It has been suggested that hypernova remnants, with a substantial amount of energy in semi-relativistic ejecta, can accelerate intermediate mass or heavy nuclei to ultra-high energies and provide sufficient amount of energy in cosmic rays to account for the observed flux. We here calculate the expected energy spectrum and chemical composition of ultra-high energy cosmic rays from such semi-relativistic hypernovae. With a chemical composition equal to that of the hypernova ejecta and a flat or hard spectrum for cosmic rays at the sources, the spectrum and composition of the propagated cosmic ra…
The measurement of the anisotropy in the arrival direction of cosmic rays is complementary to the study of their energy spectrum and chemical composition to understand their origin and propagation. It is also a tool to probe the structure of the magnetic fields through which cosmic rays travel. As cosmic rays are mostly charged nuclei, their trajectories are deflected by the action of galactic magnetic field they propagate through before reaching the Earth atmosphere, so that their detection carries directional information only up to distances as large as their gyro-radius. If cosmic rays belo…
We discuss the production of ultra high energy neutrinos coming from the propagation of ultra high energy cosmic rays and in the framework of top-down models for the production of these extremely energetic particles. We show the importance of the detection of ultra high energy neutrinos that can be a fundamental diagnostic tool to solve the discrepancy in the observed chemical composition of ultra high energy cosmic rays and, at the extreme energies, can unveil new physics in connection with the recent cosmological observations of the possible presence of tensor modes in the fluctuation patter…
扫码添加微信好友，提出您的宝贵建议 👇
💡 备注请填写：网站反馈
发表机构由 AI 从论文文本抽取，如发现错误，欢迎反馈修正建议。