7 papers
A Complete Invariant Analysis of the Kerr Spacetime and its Photon Region
Nicholas Layden, Dipanjan Dey, Alan Coley
We present an invariant characterization of the Kerr spacetime, and utilize the invariant structure of the spacetime to derive a function whose zeros identify a special family of n…
Redundancy of the cosmological evolution equations and its relationship with the initial conditions
Kaushik Bhattacharya, Dipanjan Dey, Priyanka Saha
It is known that in Friedmann-Lemaitre-Robertson-Walker cosmology one has more number of dynamical equations, compared to the number of unknown variables. This fact makes some equa…
Gravitational Collapse and Singularity Formation in Brans-Dicke Gravity
Ayush Bidlan, Dipanjan Dey, Parth Bambhaniya
We investigate gravitational collapse driven solely by a self-interacting Brans--Dicke (BD) scalar field in the absence of ordinary matter. In this framework, the spacetime dynamic…
Cosmological effect of coherent oscillation of ultralight scalar fields in a multicomponent universe
Priyanka Saha, Dipanjan Dey, Kaushik Bhattacharya
The idea that coherent oscillations of a scalar field, oscillating over a time period that is much shorter than the cosmological timescale, can exhibit cold dark matter (CDM) like…
Gravitational collapse of Matter in the presence of Scalar field Dark energy
Priyanka Saha, Dipanjan Dey, Kaushik Bhattacharya
This study examines the gravitational collapse of an overdense dark matter region in a coupled scalar field dark energy scenario within a flat FLRW background. It finds that, depen…
Non-minimal coupling of scalar fields in the dark sector and generalization of the top-hat collapse
Priyanka Saha, Dipanjan Dey, Kaushik Bhattacharya
In this article, we propose a new way to handle interactions between two scalar fields in the cosmological backdrop where one scalar field oscillates rapidly in the cosmological ti…