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In cold molecular clouds submillimetre emission lines are excited by the ambient radiation field. The pumping is dominated by the cosmic microwave background (CMB). It is usual in molecular line radiative transfer modelling to simply assume…

Astrophysics · Physics 2009-11-10 M. P. Redman , J. M. C. Rawlings , J. A. Yates , D. A. Williams

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

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

Cosmic rays are the only agent capable of ionizing the interior of dense molecular clouds and, thus, they are believed to play an essential role in determining the physical and chemical evolution of star-forming regions. In this work, we…

High Energy Astrophysical Phenomena · Physics 2024-02-09 Vo Hong Minh Phan , Enrico Peretti , Pierre Cristofari , Antoine Gusdorf , Philipp Mertsch

The spatial distribution of cosmic ray (CR) particles in the interstellar medium (ISM) is of major importance in radio astronomy, where its knowledge is essential for the interpretation of observations, and in theoretical astrophysics,…

Astrophysics of Galaxies · Physics 2023-06-28 Devika Tharakkal , Andrew P. Snodin , Graeme R. Sarson , Anvar Shukurov

We report on the effects of cosmic rays (CRs) on the abundance of CO in $\rm H_2$ clouds under conditions typical for star-forming galaxies in the Universe. We discover that this most important molecule for tracing H$_2$ gas is very…

Astrophysics of Galaxies · Physics 2015-06-23 Thomas G. Bisbas , Padelis P. Papadopoulos , Serena Viti

We study the propagation of mildly-relativistic cosmic rays (CRs) in multiphase interstellar medium environments with conditions typical of nearby disk galaxies. We employ the techniques developed in Armillotta+21 to post-process three…

Astrophysics of Galaxies · Physics 2022-05-04 Lucia Armillotta , Eve C. Ostriker , Yan-Fei Jiang

We investigate how cosmic rays (CRs) affect thermal and hydrostatic stability of circumgalactic (CGM) gas, in simulations with both CR streaming and diffusion. Local thermal instability can be suppressed by CR-driven entropy mode…

Astrophysics of Galaxies · Physics 2023-05-25 Tsun Hin Navin Tsung , S. Peng Oh , Chad Bustard

Cosmic-ray (CR) physics has been a prolific field of research for over a century. The open problems related to CR acceleration, transport and modulation are deeply connected with the indirect searches for particle dark matter (DM). In…

High Energy Astrophysical Phenomena · Physics 2016-01-12 Daniele Gaggero

We study in detail the effect of different particle release times from sources on the cosmic-ray (CR) spectrum below $10^{15}eV$ in the Galaxy. We discuss different possible forms of particle injection such as burst-like injection,…

Astrophysics · Physics 2008-11-26 Satyendra Thoudam

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

The origin of cosmic rays (CRs) has puzzled scientists since the pioneering discovery by Victor Hess in 1912. In the last decade, however, modern supercomputers have opened a new window on the processes regulating astrophysical…

High Energy Astrophysical Phenomena · Physics 2015-11-27 Damiano Caprioli

Cosmic rays (CR), constrained by scattering on magnetic irregularities, are believed to propagate diffusively. But a well-known defect of diffusive approximation whereby some of the particles propagate unrealistically fast has directed…

High Energy Astrophysical Phenomena · Physics 2016-10-11 Mikhail Malkov , Roald Sagdeev

We take a phenomenological approach in a minimal model to understand the spectral intensity of secondary cosmic-ray particles like positrons, antiprotons, Lithium, Beryllium and Boron. Our analysis shows that cosmic rays at $\sim$ GeV…

High Energy Astrophysical Phenomena · Physics 2023-09-13 Ramanath Cowsik , Dawson Huth

Stars and planets form within cold, dark molecular clouds. In these dense regions, where starlight cannot penetrate, cosmic rays (CRs) are the dominant source of ionization -- driving interstellar chemistry(Dalgarno (2006, PNAS, 103,…

Cosmological filaments, galaxy clusters, and galaxies are magnetized reservoirs of cosmic rays (CRs). The exchange of CRs across these structures is usually modeled assuming that they remain charged and magnetically confined. At high…

High Energy Astrophysical Phenomena · Physics 2026-03-27 Ellis R. Owen , Kinwah Wu , Yoshiyuki Inoue , Tatsuki Fujiwara , Qin Han , Hayden P. H. Ng

Cosmic ray (CR) feedback is critical for galaxy formation as CRs drive galactic winds, regularize star formation in galaxies, and escape from active galactic nuclei to heat the cooling cores of galaxy clusters. The feedback strength of CRs…

High Energy Astrophysical Phenomena · Physics 2024-06-10 Rouven Lemmerz , Mohamad Shalaby , Christoph Pfrommer , Timon Thomas

Recent observations have revealed that several cosmic ray (CR) sources themselves exhibit pronounced double power-law features in their radiation spectra. Combined with the phenomenon of two-component structure in the observed CR energy…

High Energy Astrophysical Phenomena · Physics 2026-02-10 Lin Nie , Yi-Qing Guo , Si-Ming Liu

A correct description of cosmic-ray (CR) diffusion in turbulent plasma is essential for many astrophysical and heliospheric problems. This paper aims to present physical diffusion behavior of CRs in actual turbulent magnetic fields, model…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Siyao Xu , Huirong Yan

Giant molecular clouds (GMCs) are a new population of gamma-ray sources, being the target of cosmic rays (CRs) -- locally accelerated or not --. These clouds host very young stellar clusters where massive star formation takes place.…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Maria Victoria del Valle , Gustavo E. Romero , Reinaldo Santos-Lima