7 papers
Apparent Phantom Crossing in Gauss-Bonnet Gravity
Shin'ichi Nojiri, Sergei D. Odintsov, V. K Oikonomou
The recent observations of the Dark Energy Spectroscopic Instrument (DESI) indicated the possibility that the dark energy equation of state parameter might change from t…
Dynamical Black Hole in the accelerating Universe approaching the future singularity -- Possible origin of (super-)massive black holes
Shin'ichi Nojiri, Sergei D. Odintsov
We construct and investigate the dynamical black hole spacetime embedded in the expanding universe filled with cosmic fluid, such as dark energy. When the equation of state (EoS) p…
Non-stationary wormholes with the presence of scalar fields and modified gravity
G. Alencar, R. Dárlla, Shin'ichi Nojiri +2
Some novel regular spacetimes are considered that show a non-stationary wormhole structure. A Simpson-Visser-like procedure is applied to reconstruct these regular spacetimes, free…
Modified gravity as entropic cosmology
Shin'ichi Nojiri, Sergei D. Odintsov, Tanmoy Paul +1
The present work reveals a direct correspondence between modified theories of gravity (cosmology) and entropic cosmology based on the thermodynamics of apparent horizon. It turns o…
Analogue of Chern-Simons invariant in non-metricity gravity and axion cosmology
Shin'ichi Nojiri, Sergei D. Odintsov
We propose a pseudo-scalar quantity, which is an analogue of the Chern-Simons invariant, in the framework of non-metricity gravity. By considering the coupling between the pseudo-s…
The correspondence of generalised entropic cosmology theory with and modified gravity and gravitational waves
Shin'ichi Nojiri, Sergei D. Odintsov
We investigate the correspondence between modified gravity theories and general entropic cosmology theory. Such a theory is proposed by an analogy with Jacobson's work, where the E…