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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 investigate the transport of spectrally resolved cosmic ray (CR) protons with kinetic energies between $1-100$ GeV within the dynamic, multiphase interstellar medium (ISM), using a two-moment CR fluid solver applied to a TIGRESS MHD…

High Energy Astrophysical Phenomena · Physics 2025-07-02 Lucia Armillotta , Eve C. Ostriker , Nora B. Linzer

Starburst galaxies are efficient $\gamma$-ray producers, because their high supernova rates generate copious cosmic ray (CR) protons, and their high gas densities act as thick targets off which these protons can produce neutral pions and…

High Energy Astrophysical Phenomena · Physics 2020-02-26 Mark R. Krumholz , Roland M. Crocker , Siyao Xu , A. Lazarian , M. T. Rosevear , Jasper Bedwell-Wilson

Galactic-scale winds are a generic feature of massive galaxies with high star formation rates across a broad range of redshifts. Despite their importance, a detailed physical understanding of what drives these mass-loaded global flows has…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Munier Salem , Greg L. Bryan

Does cosmic ray (CR) pressure matter for the circumgalactic medium (CGM)? Despite growing interest, this remains a debated question, complicated by limited observational constraints and differing implementations of CR physics in…

Astrophysics of Galaxies · Physics 2025-10-27 Manami Roy , Kung-Yi Su , Stephanie Tonnesen , Yue Samuel Lu , Cameron Hummels , Sam B. Ponnada

Cosmic ray (CR) transport and acceleration is determined by the properties of magnetic turbulence. Recent advances in MHD turbulence call for revisions in the paradigm of cosmic ray transport. We use the models of magnetohydrodynamic…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Huirong Yan

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

We explore the impact of diffusive cosmic rays (CRs) on the evolution of the interstellar medium (ISM) under varying assumptions of supernova explosion environment. In practice, we systematically vary the relative fractions of supernovae…

Astrophysics of Galaxies · Physics 2022-12-28 Christine M. Simpson , Rüdiger Pakmor , Christoph Pfrommer , Simon C. O. Glover , Rowan Smith

Galactic winds regulate star formation in disk galaxies and help to enrich the circum-galactic medium. They are therefore crucial for galaxy formation, but their driving mechanism is still poorly understood. Recent studies have demonstrated…

Astrophysics of Galaxies · Physics 2018-01-31 Svenja Jacob , Rüdiger Pakmor , Christine M. Simpson , Volker Springel , Christoph Pfrommer

Cosmic rays (CRs) play a decisive role within our own Galaxy. They provide partial pressure support against gravity, they trace past energetic events such as supernovae, and they reveal the underlying structure of the baryonic matter…

Astrophysics · Physics 2009-11-11 Torsten A. Ensslin , Christoph Pfrommer , Volker Springel , Martin Jubelgas

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

We investigate the dynamical impact of cosmic rays in cosmological simulations of galaxy formation using adaptive-mesh refinement simulations of a $10^{12}$ solar mass halo. In agreement with previous work, a run with only our standard…

Astrophysics of Galaxies · Physics 2015-06-23 Munier Salem , Greg L. Bryan , Cameron Hummels

We review numerical methods for simulations of cosmic ray (CR) propagation on galactic and larger scales. We present the development of algorithms designed for phenomenological and self-consistent models of CR propagation in kinetic…

High Energy Astrophysical Phenomena · Physics 2021-06-17 M. Hanasz , A. Strong , P. Girichidis

We study the high latitude (|b|>10) diffuse gamma-ray emission in the Galaxy in light of the recently published data from the Fermi collaboration at energies between 100 MeV and 100 GeV. The unprecedented accuracy in these measurements…

High Energy Astrophysical Phenomena · Physics 2013-04-16 I. Cholis , M. Tavakoli , C. Evoli , L. Maccione , P. Ullio

We have developed a model which aims to reproduce observational data of many kinds related to cosmic-ray (CR) origin and propagation: direct measurements of nuclei, antiprotons, electrons and positrons, gamma-rays, and synchrotron…

Astrophysics · Physics 2009-10-31 I. V. Moskalenko , A. W. Strong

The circumgalactic medium (CGM) contains information on the cumulative effect of galactic outflows over time, generally thought to be caused by feedback from star formation and active galactic nuclei. Observations of such outflows via…

Low-frequency radio observations of diffuse synchrotron radiation offer a unique vantage point for investigating the intricate relationship between gas and magnetic fields in the formation of structures within the Galaxy, spanning from the…

Astrophysics of Galaxies · Physics 2024-05-29 Andrea Bracco , Marco Padovani , Daniele Galli

We present the temporal changes of the diffusion coefficient K of galactic cosmic rays (GCRs) at the Earth orbit calculated based on the experimental data using two different methods. The first approach is based on the Parker…

Space Physics · Physics 2015-02-04 Renata Modzelewska

We study the propagation of cosmic rays (CRs) through a simulation of magnetohydrodynamic (MHD) turbulence at unprecedented resolution of $10{,}240^3$. We drive turbulence that is subsonic and super-Alfv\'enic, characterized by $\delta…

Cosmic rays (CRs) with energies $\ll$ TeV comprise a significant component of the interstellar medium (ISM). Major uncertainties in CR behavior on observable scales (much larger than CR gyroradii) stem from how magnetic fluctuations scatter…

High Energy Astrophysical Phenomena · Physics 2024-01-24 Iryna S. Butsky , Philip F. Hopkins , Philipp Kempski , Sam B. Ponnada , Eliot Quataert , Jonathan Squire