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Cosmic rays are the main agents in controlling the chemical evolution and setting the ambipolar diffusion time of a molecular cloud. We summarise the processes causing the energy degradation of cosmic rays due to their interaction with…

Astrophysics of Galaxies · Physics 2014-06-11 Marco Padovani , Patrick Hennebelle , Daniele Galli

Galactic cosmic rays (CR) are particles presumably accelerated in supernova remnant shocks that propagate in the interstellar medium up to the densest parts of molecular clouds, losing energy and their ionisation efficiency because of the…

High Energy Astrophysical Phenomena · Physics 2016-05-25 M. Padovani , A. Marcowith , P. Hennebelle , K. Ferrière

We explore the possibility that the diffuse gamma-ray background radiation (GBR) at high galactic latitudes could be dominated by inverse Compton scattering of cosmic ray (CR) electrons on the cosmic microwave background radiation and on…

Astrophysics · Physics 2009-10-31 Arnon Dar , A. De Rújula

Low-energy cosmic rays (LECRs) dominate the ionization in dense regions of molecular clouds in which other ionizers such as UV or X-ray photons are effectively shielded. Thus it was argued that the high ionization rate at the central…

High Energy Astrophysical Phenomena · Physics 2024-11-05 Bing Liu , Ruizhi Yang

Cosmic rays (CRs) leave their sources mainly along the local magnetic field; in doing so they excite both resonant and nonresonant modes through streaming instabilities. The excitation of these modes leads to enhanced scattering and in turn…

High Energy Astrophysical Phenomena · Physics 2021-06-10 Benedikt Schroer , Oreste Pezzi , Damiano Caprioli , Colby Haggerty , Pasquale Blasi

It is argued that if cosmic rays penetrate into molecular clouds, the total energy they lose can exceed the energy from galactic supernovae shocks. It is shown that most likely galactic cosmic rays interacting with the surface layers of…

Astrophysics · Physics 2009-11-10 Yu. A. Shchekinov

We investigate ionization and heating of gas in the dense, shielded clumps/cores of molecular clouds bathed by an influx of energetic, charged cosmic rays (CRs). These molecular clouds have complex structures, with substantial variation in…

Astrophysics of Galaxies · Physics 2021-06-02 Ellis R. Owen , Alvina Y. L. On , Shih-Ping Lai , Kinwah Wu

We study the combined impact of magnetic mirroring and focusing on the ionization by cosmic rays (CRs) in dense molecular clouds and circumstellar disks. We show that for effective column densities of up to $\sim10^{25}$ cm$^{-2}$ (where…

High Energy Astrophysical Phenomena · Physics 2018-08-29 Kedron Silsbee , Alexei V. Ivlev , Marco Padovani , Paola Caselli

Cosmic-rays constitute the main ionising and heating agent in dense, starless, molecular cloud cores. We reexamine the physical quantities necessary to determine the cosmic-ray ionisation rate (especially the cosmic ray spectrum at E < 1…

Astrophysics of Galaxies · Physics 2015-06-16 Marco Padovani , Daniele Galli

This paper deals with the cosmic-ray penetration into molecular clouds and with the related gamma--ray emission. High energy cosmic rays interact with the dense gas and produce neutral pions which in turn decay into two gamma rays. This…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Stefano Gabici

Cosmic rays are an essential ingredient in the evolution of the interstellar medium, as they dominate the ionisation of the dense molecular gas, where stars and planets form. However, since they are efficiently scattered by the galactic…

Astrophysics of Galaxies · Physics 2014-09-05 Solenn Vaupré , Pierre Hily-Blant , Cecilia Ceccarelli , Guillaume Dubus , Stefano Gabici , Thierry Montmerle

Cosmic rays (CRs) are the primary driver of ionization in star forming molecular clouds (MCs). Despite their potential impacts on gas dynamics and chemistry, no simulations of star cluster formation following the creation of individual…

Astrophysics of Galaxies · Physics 2024-07-26 Margot Fitz Axen , Stella Offner , Phillip F. Hopkins , Mark R. Krumholz , Michael Y. Grudic

The nature of cosmic rays (CRs) and cosmic ray transport in galaxy clusters is probed by a number of observations. Radio observations reveal the synchrotron radiation of cosmic ray electrons (CRe) spiraling around cluster magnetic fields.…

High Energy Astrophysical Phenomena · Physics 2019-06-26 Joshua Wiener , Ellen G. Zweibel

Low energy cosmic-rays (CRs) are responsible for gas heating and ionization of interstellar clouds, which in turn introduces coupling to Galactic magnetic fields. So far the CR ionization rate (CRIR) has been estimated using indirect…

Astrophysics of Galaxies · Physics 2020-11-16 Shmuel Bialy

Cosmic rays (CRs) may be used to infer properties of intervening cosmic magnetic fields. Conversely, understanding the effects of magnetic fields on the propagation of high-energy CRs is crucial to elucidate their origin. In the present…

High Energy Astrophysical Phenomena · Physics 2018-11-08 R. Alves Batista , E. M. de Gouveia Dal Pino , K. Dolag , S. Hussain

Cosmic rays (CRs) can significantly impact dense molecular clouds in galaxies, heating the interstellar medium (ISM) and altering its chemistry, ionization, and thermal properties. Their influence is particularly relevant in environments…

Astrophysics of Galaxies · Physics 2026-05-20 E. Koutsoumpou , J. A. Fernández-Ontiveros , K. M. Dasyra , L. Spinoglio

The chemistry of shielded molecular gas is primarily driven by energetic, charged particles dubbed cosmic rays (CRs), in particular those with energies under 1 GeV. CRs ionize molecular hydrogen and helium, the latter of which contributes…

Astrophysics of Galaxies · Physics 2026-04-01 Arghyadeb Roy , Brandt A. L. Gaches , Jonathan C. Tan

It is believed that the observed diffuse gamma ray emission from the galactic plane is the result of interactions between cosmic rays and the interstellar gas. Such emission can be amplified if cosmic rays penetrate into dense molecular…

Astrophysics · Physics 2008-11-26 Stefano Gabici , Felix Aharonian , Pasquale Blasi

We calculate the diffusion coefficients of charged cosmic rays (CR) propagating in regular and turbulent magnetic fields. If the magnetic field is dominated by an isotropic turbulent component, we find that CRs reside too long in the…

High Energy Astrophysical Phenomena · Physics 2018-07-24 G. Giacinti , M. Kachelriess , D. V. Semikoz

Cosmic rays are the only agent able to penetrate into the interior of dense molecular clouds. Depositing (part of) their energy through ionisation, cosmic rays play an essential role in determining the physical and chemical evolution of…

High Energy Astrophysical Phenomena · Physics 2023-06-21 Vo Hong Minh Phan , Sarah Recchia , Philipp Mertsch , Stefano Gabici