Cosmic ray production in modified gravity

Abstract

This paper is a reply to the criticism of our work on particle production in modified gravity by D. Gorbunov and A. Tokareva. We show that their arguments against efficient particle production are invalid. $F(R)$ theories can lead to an efficient generation of high energy cosmic rays in contracting systems.

In response to criticism by referees several clarifying comments are added. The results of the paper remain largely unchanged. Version to appear on EPJC