Nuclear de-excitation lines as a probe of low-energy cosmic rays

¹ Department of Astronomy, School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230026, PR China
e-mail: yangrz@ustc.edu.cn
² CAS Key Laboratory for Research in Galaxies and Cosmology, University of Science and Technology of China, Hefei, Anhui 230026, PR China
³ School of Astronomy and Space Science, University of Science and Technology of China, Hefei, Anhui 230026, PR China
⁴ Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China
⁵ Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland
⁶ Max-Planck-Institut für Kernphysik, PO Box 103980, 69029 Heidelberg, Germany
⁷ National Research Nuclear University MEPhI, Kashirskoje Shosse, 31, 115409 Moscow, Russia

Received: 24 November 2020
Accepted: 4 January 2021

Abstract

Low-energy cosmic rays (LECRs) contribute substantially to the energy balance of the interstellar medium. They play also significant role in the heating and chemistry of gas, and, consequently, on the star formation process. Because of the slow propagation coupled with enhanced energy losses of subrelativistic particles, LECRs are concentrated around their acceleration sites. LECRs effectively interact with the ambient gas through nuclear reactions. Although these processes are energetically less effective compared to heating and ionization, they are extremely important from the point of view of nuclear de-excitation lines, which carry unique information about LECRs. We present results on production of de-excitation lines combining the numerical treatment of nuclear reactions using the code TALYS, with the propagation and energy losses of LECRs.