TY - JOUR

T1 - Instabilities in modified theories of gravity

AU - Arbuzova, Elena

N1 - Funding Information: ∗Speaker. †This work was supported by the RSF Grant 19-42-02004. Publisher Copyright: © Copyright owned by the author(s) under the terms of the Creative Commons. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2019

Y1 - 2019

N2 - The review is devoted to consideration of possible observational consequences of modified gravity theories, suggested for explanation of the contemporary accelerated expansion of the universe. The major attention is paid to F(R)-models. It is shown that in systems with rising energy density high frequency and large amplitude oscillations of the curvature scalar, R(t), are induced. These oscillations lead to the production of elementary particles, which may be observed in the spectra of energetic cosmic rays. In the background of such oscillating solutions gravitation repulsion between finite-size objects becomes possible. Since the Lagrangian is a non-linear function of curvature, equations of motion become of higher (4th) order and exhibit very rich pattern of new physical effects. In particular, the evolution of density perturbations is strongly different from that in General Relativity, amplified due to both parametric resonance and anti-friction phenomena.

AB - The review is devoted to consideration of possible observational consequences of modified gravity theories, suggested for explanation of the contemporary accelerated expansion of the universe. The major attention is paid to F(R)-models. It is shown that in systems with rising energy density high frequency and large amplitude oscillations of the curvature scalar, R(t), are induced. These oscillations lead to the production of elementary particles, which may be observed in the spectra of energetic cosmic rays. In the background of such oscillating solutions gravitation repulsion between finite-size objects becomes possible. Since the Lagrangian is a non-linear function of curvature, equations of motion become of higher (4th) order and exhibit very rich pattern of new physical effects. In particular, the evolution of density perturbations is strongly different from that in General Relativity, amplified due to both parametric resonance and anti-friction phenomena.

UR - http://www.scopus.com/inward/record.url?scp=85101109531&partnerID=8YFLogxK

M3 - Conference article

AN - SCOPUS:85101109531

VL - 362

JO - Proceedings of Science

JF - Proceedings of Science

SN - 1824-8039

M1 - 026

T2 - 13th Frascati Workshops on "Multifrequency Behaviour of High Energy Cosmic Sources", MULTIF 2019

Y2 - 3 June 2019 through 8 June 2019

ER -