Grammage of cosmic rays in the proximity of supernova remnants embedded in a partially ionized medium

¹ Dipartimento di Fisica, Universitá di Torino, Via P. Giuria 1, 10125 Torino, Italy
e-mail: sarah.recchia@unito.it
² Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Via P. Giuria 1, 10125 Torino, Italy
³ INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
⁴ INAF-Osservatorio Astronomico di Brera, Via Bianchi 46, 23807 Merate, Italy
⁵ Université de Paris, CNRS, Astroparticule et Cosmologie, 75006 Paris, France
⁶ Laboratoire Univers et Particules de Montpellier, Université Montpellier/CNRS, 34095 Montpellier, France
⁷ Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation, 108840 Troitsk, Moscow, Russia

Received: 1 November 2021
Accepted: 21 January 2022

Abstract

Aims. We investigate the damping of Alfvén waves generated by the cosmic-ray resonant streaming instability in the context of cosmic-ray escape and propagation in the proximity of supernova remnants. We study in particular whether the self-confinement of cosmic rays in the vicinity of sources can appreciably affect the grammage.

Methods. We considered ion-neutral damping, turbulent damping, and nonlinear Landau damping in the warm ionized and warm neutral phases of the interstellar medium. For the ion-neutral damping, the most recent damping coefficients were used.

Results. We show that ion-neutral damping and turbulent damping effectively limit the residence time of cosmic rays in the proximity of the source, so that the grammage that is accumulated near sources is found to be negligible. In contrast to previous results, this also occurs in the most extreme scenario in which ion-neutral damping is less effective, namely in a medium consisting only of neutral helium and fully ionized hydrogen. The standard picture, in which cosmic-ray secondaries are produced during the whole time that cosmic rays spend in the Galactic disk therefore do not need to be revised substantially.