Curvature oscillations in modified gravity and high energy cosmic rays

It is shown that F( R)-modified gravitational the- ories lead to curvature oscillations in astrophysical systems with rising energy density. The frequency and the amplitude of such oscillations could be very high and would lead to noticeable production of energetic cosmic ray particles. There are two popular phenomenological explanations of the observed accelerated universe expansion. It is either pre- scribed to the existence of the so called dark energy (DE) with the equation of state P ≈− ρ,