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The hypothesis that ultra-high energy (>~ 10^19 eV) cosmic rays (UHECRs) are accelerated by gamma-ray burst (GRB) blast waves is assumed to be correct. Implications of this assumption are then derived for the external shock model of…

Astrophysics · Physics 2009-10-31 Charles D. Dermer

Feedback processes by active galactic nuclei in the centres of galaxy clusters appear to prevent large-scale cooling flows and impede star formation. However, the detailed heating mechanism remains uncertain. One promising heating scenario…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-30 Kristian Ehlert , Rainer Weinberger , Christoph Pfrommer , Rüdiger Pakmor , Volker Springel

(Abridged) The far-infrared (FIR) and radio luminosities of star-forming galaxies are linearly correlated over a very wide range in star formation rate, from normal spirals like the Milky Way to the most intense starbursts. Using one-zone…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Brian C. Lacki , Todd A. Thompson , Eliot Quataert

We use the GALPROP cosmic ray (CR) framework to model the Galactic CR distributions and associated non-thermal diffuse emissions up to PeV energies. We consider ensembles of discrete, finite lifetime CR sources, e.g.\ supernova remnants…

High Energy Astrophysical Phenomena · Physics 2025-01-29 P. D. Marinos , T. A. Porter , G. P. Rowell , G. Jóhannesson , I. V. Moskalenko

The X-ray emission properties from the hot thermalized plasma that results from the collisions of individual stellar winds and supernovae ejecta within rich and compact star clusters are discussed. We propose a simple analytical way of…

Gamma-ray data from Fermi-LAT reveal a bi-lobular structure extending up to 50 degrees above and below the galactic centre, which presumably originated in some form of energy release there less than a few million years ago. It has been…

High Energy Astrophysical Phenomena · Physics 2011-08-26 Philipp Mertsch , Subir Sarkar

We investigate the dynamical interaction between cosmic rays (CRs) and the multiphase interstellar medium (ISM) using numerical magnetohydrodynamic (MHD) simulations with a two-moment CR solver and TIGRESS simulations of star-forming…

Astrophysics of Galaxies · Physics 2024-01-10 Lucia Armillotta , Eve C. Ostriker , Chang-Goo Kim , Yan-Fei Jiang

The Fermi bubbles are two large structures in the gamma-ray sky extending to $55^\circ$ above and below the Galactic center. We analyze 50 months of Fermi Large Area Telescope data between 100 MeV and 500 GeV above $10^\circ$ in Galactic…

High Energy Astrophysical Phenomena · Physics 2014-09-22 LAT Collaboration

We study the synchrotron radio emission from extra-planar regions of star forming galaxies. We use ideal magneto-hydrodynamical (MHD) simulations of a rotating Milky Way-type disk galaxy with distributed star formation sites for three star…

Astrophysics of Galaxies · Physics 2020-01-08 Aditi Vijayan , Biman B. Nath , Prateek Sharma , Yuri Shchekinov

We present an extensive analysis of the multi-wavelength data of the low-synchrotron-peaked BL Lac object CGRaBS J0211+1051, which has been gathered over more than ten years with many observatories. Two major gamma-ray flares have been…

High Energy Astrophysical Phenomena · Physics 2025-11-14 Sunil Chandra , Pankaj Kushwaha , Pranjupriya Goswami , Michael Zacharias

Hadronic emission from parsec size radio lobes in active galactic nuclei (AGN) is discussed. The lobes are composed of shocked jet plasmaand expected to be filled with high energy particles. By using the Monte Carlo simulation, we calculate…

High Energy Astrophysical Phenomena · Physics 2010-06-18 Motoki Kino , Katsuaki Asano

During the past few years, first observations of starburst galaxies at >GeV energies could be made with the Fermi Gamma-ray Space Telescope (GeV range) and Imaging Air Cherenkov Telescopes (TeV range). The two nearest starbursts, M82 and…

High Energy Astrophysical Phenomena · Physics 2011-07-22 J. K. Becker , F. Schuppan , S. Schoeneberg

The wealth of recent data from imaging air Cherenkov telescopes (IACTs), ultra-high energy cosmic-ray experiments and neutrino telescopes have fuelled a renewed interest in hadronic emission models for gamma-loud blazars. We explore…

High Energy Astrophysical Phenomena · Physics 2017-06-08 Andreas Zech , Matteo Cerruti , Daniel Mazin

Recent observations of VER J2227+608 reveal a broken power $\gamma$-ray spectrum with the spectral index increasing from $\sim 1.8$ in the GeV energy range to $\sim 2.3$ in the TeV range. Such a spectral break can be attributed to radiative…

High Energy Astrophysical Phenomena · Physics 2020-07-22 Siming Liu , Houdun Zeng , Yuliang Xin , Hui Zhu

The AMS Collaboration has recently released data on cosmic ray (CR) leptons and hadrons that can shed light on two exciting problems in CR physics: on one side, the origin of the rise of the CR positron fraction above ~10 GeV of energy, on…

High Energy Astrophysical Phenomena · Physics 2015-11-02 Nicola Tomassetti

Cosmic rays (CRs) are a pivotal non-thermal component of galaxy formation and evolution. However, the intricacies of CR physics, particularly how they propagate in the circumgalactic medium (CGM), remain largely unconstrained. In this work,…

Molecular clouds are expected to emit non-thermal radiation due to cosmic ray interactions in the dense magnetized gas. Such emission is amplified if a cloud is located close to an accelerator of cosmic rays and if energetic particles can…

High Energy Astrophysical Phenomena · Physics 2015-05-13 Stefano Gabici , Felix A. Aharonian , Sabrina Casanova

Feedback mediated by cosmic rays (CRs) is an important process in galaxy formation. Because CRs are long-lived and because they are transported along magnetic field lines independently of any gas flow, they can efficiently distribute their…

Astrophysics of Galaxies · Physics 2022-03-24 Timon Thomas , Christoph Pfrommer , Rüdiger Pakmor

A joint hadronic model is shown to quantitatively explain the observations of diffuse radio emission from galaxy clusters in the form of minihalos, giant halos, relics, and their hybrid, transitional stages. Cosmic-ray diffusion of order…

High Energy Astrophysical Phenomena · Physics 2023-11-16 Uri Keshet

In this review, recent progress in theoretical models for the broadband (radio through gamma-ray) emission from blazars are summarized. The salient features of both leptonic and hadronic models are reviewed. I present sample modeling…

Cosmology and Nongalactic Astrophysics · Physics 2012-05-03 Markus Boettcher
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