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High-energy gamma rays of interstellar origin are produced by the interaction of cosmic-ray (CR) particles with the diffuse gas and radiation fields in the Galaxy. The main features of this emission are well understood and are reproduced by…

High Energy Astrophysical Phenomena · Physics 2017-09-06 Troy A. Porter , Gudlaugur Johannesson , Igor V. Moskalenko

Cosmic rays (CRs) are ubiquitous in the interstellar medium (ISM) of nearby galaxies, but many of their properties are not well-constrained. Gamma-ray observations provide a powerful tool in this respect, allowing us to constrain both the…

High Energy Astrophysical Phenomena · Physics 2023-07-19 Maria Werhahn , Philipp Girichidis , Christoph Pfrommer , Joseph Whittingham

The present status of anisotropy studies for the highest energy cosmic rays is presented including the first full sky survey. Directions and prospects for the future are also discussed in light of new statistical methods and the last…

Astrophysics · Physics 2016-11-09 John Swain

Ultra-high-energy cosmic rays (UHECRs) are the most energetic particles known - and yet their origin is still an open question. However, with the precision and accumulated statistics of the Pierre Auger Observatory and the Telescope Array,…

High Energy Astrophysical Phenomena · Physics 2025-11-10 Teresa Bister

Conventional cosmic-ray propagation models usually assume an isotropic diffusion coefficient to account for the random deflection of cosmic rays by the turbulent interstellar magnetic field. Such a picture is very successful in explaining…

High Energy Astrophysical Phenomena · Physics 2020-03-24 Wei Liu , Su-jie Lin , Hong-bo Hu , Yi-qing Guo , Ai-feng Li

We study the small scale anisotropy signal expected at the Pierre Auger Observatory in the next 1, 5, 10, and 15 years of operation, from sources of ultra-high energy (UHE) protons. We numerically propagate UHE protons over cosmological…

Astrophysics · Physics 2009-11-11 Daniel De Marco , Pasquale Blasi , Angela V. Olinto

A leading way to constrain physical theories from cosmological observations is to test their predictions for the angular clustering statistics of matter tracers, a technique that is set to become ever more central with the next generation…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-17 Antón Baleato Lizancos , Martin White

The origin of the highest-energy cosmic rays remains a mystery. The lack of a high energy cutoff in the cosmic ray spectrum together with an apparently isotropic distribution of arrival directions have strongly constrained most models…

Astrophysics · Physics 2010-12-03 A. V. Olinto

The nuclei fraction in cosmic rays (CR) far exceeds the fraction of other CR species, such as antiprotons, electrons, and positrons. Thus the majority of information obtained from CR studies is based on interpretation of isotopic abundances…

Astrophysics · Physics 2009-11-10 I. V. Moskalenko , A. W. Strong , S. G. Mashnik

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with $E \geq 6 \cdot 10^{19}$ eV by analyzing…

High Energy Astrophysical Phenomena · Physics 2015-12-03 The Pierre Auger Collaboration

We calculate the number density and luminosity of the sources of ultra high energy cosmic rays (UHECRs), using the information about the small scale anisotropies and the observed spectra. We find that the number of doublets and triplets…

Astrophysics · Physics 2008-11-26 Pasquale Blasi , Daniel De Marco

Cosmic rays that escape their acceleration site interact with the ambient medium and produce gamma rays as the result of inelastic proton-proton collisions. The detection of such diffuse emission may reveal the presence of an accelerator of…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Lara Nava , Stefano Gabici

The large-scale dipolar structure in the arrival directions of ultra-high-energy cosmic rays with energies above $8\,$EeV observed by the Pierre Auger Collaboration is a well-established anisotropy measurement. This anisotropy is understood…

High Energy Astrophysical Phenomena · Physics 2025-07-24 G. Golup

The observational evidence regarding the present cosmological aspects tells us about the presence of very little anisotropy in the universe on a large scale. Here, in this paper, we attempt to study locally rotationally symmetric (LRS)…

General Relativity and Quantum Cosmology · Physics 2022-11-02 N. S. Kavya , V. Venkatesha , Sanjay Mandal , P. K. Sahoo

We propose and test new statistical tools to study the distribution of cosmic rays based on the use of the Minimal Spanning Tree. The method described is particularly sensitive to filamentary structures, as those expected to arise from…

Astrophysics · Physics 2009-11-11 Diego Harari , Silvia Mollerach , Esteban Roulet

The origin of cosmic rays (CRs) and how they propagate remain unclear. Studying the propagation of CRs in magnetohydrodynamic (MHD) turbulence can help to comprehend many open issues related to CR origin and the role of turbulent magnetic…

High Energy Astrophysical Phenomena · Physics 2025-01-10 Na-Na Gao , Jian-Fu Zhang

In the standard diffusive picture for transport of cosmic rays (CRs), a gradient in the CR density induces a typically small, dipolar anisotropy in their arrival directions. This has been widely advertised as a tool for finding nearby…

High Energy Astrophysical Phenomena · Physics 2015-01-15 Philipp Mertsch , Stefan Funk

We present a Bayesian hierarchical modelling approach to infer the cosmic matter density field, and the lensing and the matter power spectra, from cosmic shear data. This method uses a physical model of cosmic structure formation to infer…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-03 Natalia Porqueres , Alan Heavens , Daniel Mortlock , Guilhem Lavaux

Several hypothesis testing methods have been proposed to validate the assumption of isotropy in spatial point patterns. A majority of these methods are characterised by an unknown distribution of the test statistic under the null hypothesis…

Methodology · Statistics 2025-04-09 Jakub J. Pypkowski , Adam M. Sykulski , James S. Martin

We use the GALPROP code and the Advanced Composition Explorer (ACE) data to derive the cosmic ray (CR) isotopic composition at the sources. The composition is derived for two propagation models, diffusive reacceleration and plain diffusion.…

Astrophysics · Physics 2009-02-25 Igor V. Moskalenko , Andrew W. Strong , Troy A. Porter