753 citations · 757 across the 12 of their papers we have counts for
12 papers
Boundary-Geometry-Driven Black Hole Formation in Vacuum
Dipanjan Dey, Puskar Mondal, Shing-Tung Yau
We identify a boundary-geometry-driven mechanism for the dynamical formation of marginally outer trapped surfaces (MOTSs) in vacuum general relativity. Mild three-dimensional aniso…
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…
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…
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…
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…
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…
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…
The Definition of a Photon Surface in an Invariant Spin Frame
Dipanjan Dey, Alan A. Coley, Nicholas T. Layden
This paper defines the photon surface conditions using Cartan scalars within an invariant spin frame, offering a comprehensive description of the local spacetime geometry. By emplo…
Invariant description of static and dynamical Brans-Dicke spherically symmetric models
Nicholas Layden, Alan Coley, Dipanjan Dey
We investigate spherically symmetric static and dynamical Brans-Dicke theory exact solutions using invariants and, in particular, the Newman Penrose formalism utilizing Cartan scal…
Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A
Sunny Vagnozzi, Rittick Roy, Yu-Dai Tsai +12
Horizon-scale images of black holes (BHs) and their shadows have opened an unprecedented window onto tests of gravity and fundamental physics in the strong-field regime. We conside…