9 papers · 1 filter
Black holes and their shadows in gravity
Shin'ichi Nojiri, S. D. Odintsov
We investigate the radii of the photon sphere and the black hole shadow in the framework of gravity. For this purpose, we derive the field equation for the corresponding the…
Black holes, photon sphere, and cosmology in ghost-free gravity
Shin'ichi Nojiri, S. D. Odintsov
The improved version of ghost-free gravity introduced in Phys.~Lett.~B \textbf{631} (2005), 1-6 is proposed and investigated. It is demonstrated that improved ghos…
Improving Mimetic Gravity with Non-trivial Scalar Potential: Cosmology, Black Holes, Shadow and Photon Sphere
Shin'ichi Nojiri, Sergei D. Odintsov
It is not easy to treat the spacetime with horizon(s) in the standard mimetic gravity. The solution to this problem has been presented in Phys.~Lett.~B 830 (2022), 137140, where it…
Future singularity in an anisotropic universe
Taishi Katsuragawa, Shin'ichi Nojiri, Sergei D. Odintsov
We investigate future singularities originating from the anisotropy in the Universe. We formulate a new class of singularities in the homogeneous and anisotropic universe, comparin…
Different aspects of entropic cosmology
Shin'ichi Nojiri, Sergei D. Odintsov, Tanmoy Paul
We give a short review of the recent developments of entropic cosmology based on two thermodynamic laws of the apparent horizon, namely the first and the second laws of thermodynam…
gravity with Gauss-Bonnet corrections: from early-time inflation to late-time acceleration
Shin'ichi Nojiri, S. D. Odintsov
We show that in the gravity with a non-metricity scalar , the curvatures in Einstein's gravity, that is, the Riemann curvature constructed from the standard Levi-Civita c…