We propose and discuss a $\psi$-diagram a novel kind of a plot representing light-like geodesics. We consider spherically symmetric, static spacetimes. The general construction is illustrated with diagrams for light rays in the proximity of the Schwarzschild, Reissner–Nordstrom (charged) and Kerr (rotating) types of black holes.
The idea is developed from the phase portraits illustrating the...
Wave optics aspects of image formation in strong gravitational fields (in a vicinity of a black hole’s horizon) are discussed. We consider two observers A and B placed (co) radially, r(A)<r(B) within Schwarzschild spacetime. The case of an image formation of an isotropic source of light placed at A in terms of lens arranged at B is analyzed. Emission (A) and propagation (AB) of the null...
An intervening galaxy acts like a gravitational lens and produce multiple images of a single source such as a remote galaxy. Such galaxies have peculiar speeds in addition to the bulk motion appearing due to the expansion of the universe. There is a difference in light arriving time known as the time delay. We calculate more realistic time delays when such peculiar motions are taken into consideration.
Cosmological perturbations along with the background cosmology, in light mass Galileon scenario, will be discussed. Light mass Galileon is a cubic Galileon model with potential and nonminimal coupling. Effects of the nonminimal coupling on power spectrum and bispectrum will be discussed.
It is well known that the study of many-body systems in the presence of long-range interactions (1/r^a, a>1) within the context of Boltzmann-Gibbs statistical mechanics is unsuccessful. The configurational integral contained in the partition function diverges, preventing us from a proper probabilistic analysis of the system. This motivates us to describe our system by a non-additive and...
