Abstract
This paper is a reply to the criticism of our work on particle production in modified gravity by Gorbunov and 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.
Highlights
In our paper [1] we have found that in some versions ofF(R)-theories curvature scalar R reaches infinity in objects with a rising mass/energy density, as first predicted in [2] and further investigateds in [3]
We agree with the GT choice, but using it and numerically proceeding from t2 to t1, we have found that the value of y at t1 is roughly the same as it was guessed in our work
As we have shown explicitly in the previous section, even starting from purely general relativity (GR) initial conditions, the increasing external density acts as a source term for curvature oscillations and moves solutions away from GR
Summary
F(R)-theories curvature scalar R reaches infinity in objects with a rising mass/energy density, as first predicted in [2] and further investigateds in [3]. The singularity can be avoided if an R2-term [4] is added to the action In this case R remains finite but reaches very large values in the process of high frequency oscillations. In our papers [6,7] we argued that such high frequency oscillations could lead to an efficient production of energetic particles, which may in principle give a noticeable contribution to the flux of energetic cosmic rays. These results have been recently criticized by Gorbunov and Tokareva (GT from here on) in Refs.
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