Some Observable Effects of Modified Gravity in Cosmology and Astrophysics

Abstract

In Chapter 1 I present the current picture of the universe and briefly review the cosmological constant problem and some of the theories proposed to solve it. The following Chapters essentially contain the published papers with some modifications and additions: in Chapter 2 I study the radiation-dominated epoch in $R^2$ gravity, gravitational particle production and its implications for the early and contemporary universe; in Chapter 3 I investigate the formation of curvature singularities in contracting astronomical systems; in Chapter 4, I discuss some mechanisms to prevent such singularities and calculate the related cosmic-ray production; finally, in Chapter 5, I deal with spherically symmetric solutions and explore the possibility of gravitational repulsion.

arXiv commentDoctoral thesis successfully defended in March 2014, grade: Excellent. Advisor: Prof. A.D. Dolgov. Part of the work done in collaboration with E.V. Arbuzova.

References in corpus (18)

• Disappearing cosmological constant in f(R) gravity
• First Observation of the Greisen-Zatsepin-Kuzmin Suppression
• Towards singularity and ghost free theories of gravity
• Super-renormalizable Quantum Gravity
• Curing singularities in cosmological evolution of F(R) gravity
• A Singularity Problem with f(R) Dark Energy
• Relativistic stars in f(R) gravity, and absence thereof
• Jeans analysis of self-gravitating systems in f(R)-gravity
• Gravitational collapse in f(R) theories
• Time-dependent matter instability and star singularity in $F(R)$ gravity
• Relativistic stars in f(R) and scalar-tensor theories
• Relativistic stars in f(R) gravity
• Observation of the Ankle and Evidence for a High-Energy Break in the Cosmic Ray Spectrum
• Constraining $f(R)$ gravity models with disappearing cosmological constant
• The Pierre Auger Observatory I: The Cosmic Ray Energy Spectrum and Related Measurements
• Sensitivity of cosmic-ray experiments to ultra-high-energy photons: reconstruction of the spectrum and limits on the superheavy dark matter
• Reheating after f(R) inflation
• How delicate are the $f(R)$ gravity models with disappearing cosmological constant?

Cited by in corpus (1)

• Gravitational Wave Signatures from Domain Wall and Strong First-Order Phase Transitions in a Two Complex Scalar extension of the Standard Model