9 citations · 17 across the 12 of their papers we have counts for
14 papers
Constant-Roll Inflation as a Competitive Alternative to Slow-Roll Inflation
Sandip Biswas, Rajib Saha, Kaushik Bhattacharya
Starting from the constant-roll condition, which involves the constant-roll parameter , which is a fundamental constant in the constant-roll inflationary models, we derive the s…
Sub-Horizon and Quasi-Static Approximations in Interacting Dark Sector Models Involving Scalar Field Dark Energy
Priyanka Saha, Sharvari Nadkarni-Ghosh, Kaushik bhattacharya
We investigate the validity of the sub-horizon approximation (SHA) and quasi-static approximation (QSA) for linear matter perturbations in interacting scalar-field dark-energy mode…
A Potential Black Hole Mimicker From Non-Minimal Coupling
Debanjan Debnath, Rikpratik Sengupta, Kaushik Bhattacharya
We present a class of horizonless, regular ultra-compact objects arising in a theory of gravity that allows curvature-fluid coupling. The non-minimal interaction between fluid vari…
Junction Conditions and Gravitational Collapse in Scalar-Tensor-Vector Gravity
Debanjan Debnath, Anant Badal, Kaushik Bhattacharya
We formulate the junction conditions for Scalar-Tensor-Vector Gravity (STVG/MOG), proposed by J.~W.~Moffat. Using these conditions, the theory of gravitational collapse is construc…
Bounce, Turnaround, and the Anisotropy Problem in Cyclic Cosmology on a Brane with a Timelike Extra Dimension
Rikpratik Sengupta, Arkajit Aich, Kaushik Bhattacharya
We study cosmological bounces, turnarounds, and cyclic evolution on an anisotropic Bianchi-I brane embedded in a five-dimensional bulk with a \emph{timelike} extra dimension, withi…
Spherically Symmetric, Static Solutions in Presence of Matter-Curvature Coupling
Debanjan Debnath, Kaushik Bhattacharya
In this work we have proposed some spherically symmetric, static spacetimes in a theory of gravity which permits non-minimal coupling (NMC) between curvature of spacetime and fluid…
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…
Dynamical systems approach to Cold and Warm Inflation within slow-roll and beyond
Sandip Biswas, Saddam Hussain, Kaushik Bhattacharya
In this work, we systematically present a new dynamical systems approach to standard inflationary processes and their variants as constant-roll inflation. Using the techniques pres…
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…
End equilibrium state of a spherical gravitational collapse in the presence of matter and scalar field
Debanjan Debnath, Dipanjan Dey, Kaushik Bhattacharya
We explore the possibilities of modeling a spherically symmetric static spacetime that can emerge as the end state of gravitational collapse, by considering it to be seeded by a co…
Reassessing constant-roll Warm Inflation
Sandip Biswas, Kaushik Bhattacharya, Suratna Das
Departing from standard slow-roll conditions is one way of putting the inflationary paradigm to test, and constraining the dynamics of the inflaton field with a constant-rate of ro…
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 of matter in the presence of non-minimally coupled Quintessence and Phantom-like scalar fields
Priyanka Saha, Dipanjan Dey, Kaushik Bhattacharya
This paper explores the evolution of the over-dense region of dark matter in the presence of a non-minimally coupled scalar field which is used to model quintessence and phantom-li…
Embedding Ultra slow-roll inflaton dynamics in Warm Inflation
Sandip Biswas, Kaushik Bhattacharya, Suratna Das
Slow-roll of the inflaton field defines the standard dynamics of the inflationary epoch. However, the inflationary system deviates from slow-roll when it encounters an extremely fl…