10 citations · 32 across the 16 of their papers we have counts for
17 papers
Transmutation Timescales for Dark Matter Induced Collapse of Compact Stars into Black Holes
H. A. Adarsha, Chandrachur Chakraborty, Sudip Bhattacharyya
Ultra-heavy asymmetric dark matter (DM) particles captured by compact stars can thermalize, self-gravitate, and collapse to form an endoparasitic black hole (EBH), whose subsequent…
Relativistic outflows power a quasi-periodic eruption: constraints on energetics, mass loss, and emission mechanisms
Joheen Chakraborty, Erin Kara, Wenbin Lu +17
Quasi-periodic eruptions (QPEs) are recurring bursts of X-ray radiation originating from supermassive black holes (SMBHs). They are an unprecedented type of structured, high-amplit…
Tilted thin accretion disks in the full Kerr spacetime and their implications
K. S. Sruthy, Chandrachur Chakraborty, Sudip Bhattacharyya
We derive a steady-state warped-disk equation in the full Kerr spacetime to study the tilt dynamics of a thin, viscous accretion disk around a spinning collapsed object. The formul…
A NICER and AstroSat view of the neutron star low-mass X-ray binary 1A 1246-588
Vaidehi Poojyam, Vikas Mistry, Yash Bhargava +2
Neutron star (NS) low-mass X-ray binary (LMXB) systems depict a variety of X-ray spectral and timing features, which can be useful to probe the accretion-ejection mechanism in the…
Degeneracy in Accretion Disk Spectra from Naked Singularities and Kerr Black Holes: Application to the AGN MCG-06-30-15
Vishva Patel, Sayantan Bhattacharya, Sudip Bhattacharyya +1
Theoretical studies suggest that gravitational collapse can form either a black hole or a visible (naked) singularity. Identifying observational signatures that distinguish these t…
Explainable machine learning classification of \textit{Chandra} X-ray sources: SHAP analysis of multi-wavelength features
Shivam Kumaran, Samir Mandal, Sudip Bhattacharyya
Extensive astronomical surveys, like those conducted with the {\em Chandra} X-ray Observatory, detect hundreds of thousands of unidentified cosmic sources. Machine learning (ML) me…
Tidal disruption of a neutron star near naked singularity
Ashok B. Joshi, Pankaj S. Joshi, Sudip Bhattacharyya
We investigate the tidal disruption of a neutron star (NS) near a black hole (BH), and for the first time, to the best of our knowledge, near a naked singularity (NaS). For a BH wi…
Accretion inside astrophysical objects : Effects of rotation and viscosity
H. A. Adarsha, Chandrachur Chakraborty, Sudip Bhattacharyya
Sub-solar mass black holes could show up in gravitational wave observations in future and near-solar mass black holes might have been involved in the events GW190425 and GW190814.…
Magnetically arrested transmutation of a compact star
H. A. Adarsha, Chandrachur Chakraborty, Sudip Bhattacharyya
We introduce a novel mechanism -- Magnetically Arrested Transmutation (MAT) -- which could be a viable model to account for the observed over-representation of magnetic white dwarf…
On Formation of Primordial Naked Singularities
Koushiki, Pankaj S. Joshi, Sudip Bhattacharyya
The density fluctuations in the nearly homogeneous background in the very early universe are argued to be the origin of the cosmic structures we observe in our present universe. Al…
AstroSat timing and spectral analysis of the accretion-powered millisecond X-ray pulsar IGR J17591--2342
Akshay Singh, Andrea Sanna, Sudip Bhattacharyya +5
IGR J17591--2342, a transient accretion-powered millisecond X-ray pulsar, was discovered during its 2018 outburst. Here, we present a timing and spectral analysis of the source usi…
Probing properties of nearly two-hundred new active galactic nuclei
Samrat Ghosh, Samir Mandal, Sudip Bhattacharyya +1
We present a comprehensive analysis of the X-ray spectral properties of 198 newly identified active galactic nuclei (AGNs), leveraging archival data from the {\it Chandra} X-ray Ob…
Study of a Tilted Thin Accretion Disk around a Kerr-Taub-NUT black hole
Gargi Sen, Chandrachur Chakraborty, Sudip Bhattacharyya +3
The accreting collapsed object GRO J1655-40 could contain the gravitomagnetic monopole (GMM), and it was shown to be better described by the Kerr-Taub-NUT (KTN) spacetime instead o…
Low Mass Naked Singularities from Dark Core Collapse
Chandrachur Chakraborty, Sudip Bhattacharyya, Pankaj S. Joshi
Near-solar mass black holes (BHs) could have been involved in the two recent gravitational wave events, GW190425 and GW190814. Since such a low mass BH cannot be formed via stellar…
Primordial naked singularities
Pankaj S. Joshi, Sudip Bhattacharyya
Primordial black hole formation has been discussed widely, when density perturbations in the early universe cause matter to collapse gravitationally, giving rise to these ultra-com…
Near- and sub-solar-mass naked singularities and black holes from transmutation of white dwarfs
Chandrachur Chakraborty, Sudip Bhattacharyya
Recent gravitational wave events have suggested the existence of near-solar-mass black holes which cannot be formed via stellar evolution. This has opened up a tantalizing possibil…
Revealing Physical Properties of a Tidal Disruption Event: iPTF16fnl
Mageshwaran Tamilan, Gargi Shaw, Sudip Bhattacharyya +1
Tidal disruption event (TDE) iPTF16fnl shows a relatively low optical flare with observationally very weak X-ray emission and the spectroscopic property that the helium emission li…