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Low-energy (~MeV) cosmic rays (CRs) ionize molecular clouds and create the neutral iron line (Fe I K\alpha) at 6.4 keV. On the other hand, high-energy (>~ GeV) CRs interact with the dense cloud gas and produce gamma rays. Based on a…

High Energy Astrophysical Phenomena · Physics 2021-02-22 Yutaka Fujita , Kumiko K. Nobukawa , Hidetoshi Sano

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

The microphysics of ~GeV cosmic ray (CR) transport on galactic scales remain deeply uncertain, with almost all studies adopting simple prescriptions (e.g. constant-diffusivity). We explore different physically-motivated, anisotropic,…

High Energy Astrophysical Phenomena · Physics 2022-03-18 Philip F. Hopkins , Jonathan Squire , T. K. Chan , Eliot Quataert , Suoqing Ji , Dusan Keres , Claude-Andre Faucher-Giguere

Recent efforts in cosmic ray (CR) confinement and transport theory are discussed. Three problems are addressed as being crucial for understanding the present day observations and their possible telltale signs of the CR origin. The first…

High Energy Astrophysical Phenomena · Physics 2016-10-11 M. A. Malkov

We compare the $\gamma$-ray spectra from 10 middle-aged supernova remnants (SNRs), which are interacting with molecular clouds (MCs), with the model prediction from widely used escaping scenario and direct interaction scenario. It is found…

High Energy Astrophysical Phenomena · Physics 2018-08-15 Xiaping Tang

We analyse the results of recent measurements of nonthermal emission from individual supernova remnants (SNRs) and their correspondence to the nonlinear kinetic theory of cosmic ray (CR) acceleration in SNRs. It is shown that the theory…

Astrophysics · Physics 2008-11-26 E. G. Berezhko

We investigate the impact of cosmic rays (CRs) on galactic outflows from a multi-phase interstellar medium with solar neighbourhood conditions. The three-dimensional magneto-hydrodynamical simulations include CRs as a relativistic fluid in…

Astrophysics of Galaxies · Physics 2018-07-11 Philipp Girichidis , Thorsten Naab , Michał Hanasz , Stefanie Walch

We investigate the possibility of cosmic ray (CR) confinement by charged dust grains through resonant drag instabilities (RDIs). We perform magnetohydrodynamic particle-in-cell simulations of magnetized gas mixed with charged dust and…

High Energy Astrophysical Phenomena · Physics 2022-04-25 Suoqing Ji , Jonathan Squire , Philip F. Hopkins

Galactic cosmic rays (CRs) are accelerated at the forward shocks of supernova remnants (SNRs) via diffusive shock acceleration (DSA), an efficient acceleration mechanism that predicts power-law energy distributions of CRs. However,…

High Energy Astrophysical Phenomena · Physics 2021-11-24 Rebecca Diesing , Damiano Caprioli

The time-dependent nonlinear kinetic theory for cosmic ray (CR) acceleration in supernova remnants (SNRs) is applied studying the properties of the synchrotron emission from SNRs, in particular, the surface brightness-diameter ($\Sigma-D$)…

Astrophysics · Physics 2009-11-10 E. G. Berezhko , H. J. Völk

For the case of Tycho's supernova remnant (SNR) we present the relation between the blast wave and contact discontinuity radii calculated within the nonlinear kinetic theory of cosmic ray (CR) acceleration in SNRs. It is demonstrated that…

Astrophysics · Physics 2008-11-26 H. J. Voelk , E. G. Berezhko , L. T. Ksenofontov

Low-energy cosmic rays (CRs) are confined by self-generated MHD waves in the mostly neutral ISM. We show that the CR transport equation can be expressed as a continuity equation for the CR number density involving an effective convection…

Astrophysics · Physics 2009-11-10 Paolo Padoan , John Scalo

Understanding the cosmic ray (CR) ionization rate is crucial in order to simulate the dynamics of, and interpret the chemical species observed in molecular clouds. Calculating the CR ionization rate requires both accurate knowledge of the…

High Energy Astrophysical Phenomena · Physics 2019-07-10 Kedron Silsbee , Alexei V. Ivlev

In the standard Galactic cosmic-ray (CR) paradigm, protons are accelerated up to ~1 PeV by Galactic sources. While supernova remnants (SNRs) have been traditionally considered as the primary accelerators, recent observations by LHAASO and…

High Energy Astrophysical Phenomena · Physics 2026-01-22 Yutaka Fujita , Rohta Takahashi , Norita Kawanaka

Galactic cosmic rays (CRs) are believed to be accelerated at supernova remnant (SNR) shocks. In the hadronic scenario the TeV gamma-ray emission from SNRs originates from decaying pions that are produced in collisions of the interstellar…

High Energy Astrophysical Phenomena · Physics 2020-06-24 Matteo Pais , Christoph Pfrommer , Kristian Ehlert , Maria Werhahn , Georg Winner

The contribution of the Source Cosmic Rays (SCRs), confined in Supernova Remnants, to the diffuse high energy \gr emission above 1 GeV from the Galactic disk is studied. \grs produced by the SCRs have a much harder spectrum compared with…

Astrophysics · Physics 2010-12-03 Evgeny G. Berezhko , Heinrich J. Voelk

Recent results obtained by analyzing diffuse gamma-ray emission detected by Fermi-LAT show a substantial variation of the CR spectrum as a function of the distance from the Galactic Center. For energies up to tens of GeV, the CR proton…

High Energy Astrophysical Phenomena · Physics 2017-06-21 G. Morlino

We review recent progress in elucidating the relationship between high-energy radiation and the interstellar medium (ISM) in young supernova remnants (SNRs) with ages of $\sim$2000 yr, focusing in particular on RX J1713.7$-$3946 and RCW 86.…

High Energy Astrophysical Phenomena · Physics 2021-06-29 Hidetoshi Sano , Yasuo Fukui

The propagation of particles accelerated at supernova remnant shocks and escaping the parent remnants is likely to proceed in a strongly non-linear regime, due to the efficient self-generation of Alfv\'en waves excited through streaming…

High Energy Astrophysical Phenomena · Physics 2017-12-27 M. D'Angelo , G. Morlino , E. Amato , P. Blasi

We performed kinetic simulations of diffusive shock acceleration in Type Ia supernova remnants (SNRs) expanding into a uniform interstellar medium (ISM). The preshock gas temperature is the primary parameter that governs the cosmic ray (CR)…

High Energy Astrophysical Phenomena · Physics 2011-05-20 Hyesung Kang