56 citations · 151 across the 21 of their papers we have counts for
21 papers
Improved Constraints on Non-Kerr Deviations from Binary Black Hole Inspirals Using GWTC-4 Data
Debtroy Das, Swarnim Shashank, Cosimo Bambi
Gravitational wave (GW) observations of binary black hole (BBH) mergers provide a unique opportunity to probe the nature of spacetime in the strong-field and dynamical regime. We p…
Bright flare in the obscured state of GRS 1915+105 as seen by NICER and Swift
Shuaitongze Zhao, Honghui Liu, Menglei Zhou +3
We report time-resolved NICER and Swift X-ray spectroscopy of a bright flare from the black hole X-ray binary GRS 1915+105 during its obscured state, which is characterized by heav…
Testing non-circular black hole spacetime with X-ray reflection
Leda Gao, Swarnim Shashank, Cosimo Bambi
X-ray reflection spectroscopy is a powerful tool for testing the Kerr hypothesis and probing the strong gravity regime around accreting black holes. Most tests of General Relativit…
Testing black hole metrics with binary black hole inspirals
Zhe Zhao, Swarnim Shashank, Debtroy Das +1
Gravitational wave astronomy has opened an unprecedented window onto tests of gravity and fundamental physics in the strong-field regime. In this study, we examine a series of well…
X-ray reflection spectroscopy with improved calculations of the emission angle
Yimin Huang, Honghui Liu, Temurbek Mirzaev +10
The reflection spectrum produced by a cold medium illuminated by X-ray photons is not isotropic and its shape depends on the emission angle. In the reflection spectrum of an accret…
Measuring black hole spins with x-ray reflection spectroscopy: A GRMHD outlook
Swarnim Shashank, Askar B. Abdikamalov, Honghui Liu +4
X-ray reflection spectroscopy has evolved as one of the leading methods to measure black hole spins. However, the question is whether its measurements are subjected to systematic b…
Quasi-normal modes of slowly-rotating Johannsen black holes
Yuhao Guo, Swarnim Shashank, Cosimo Bambi
The detection of gravitational waves with ground-based laser interferometers has opened a new window to test and constrain General Relativity (GR) in the strong, dynamical, and non…
Observing the eye of the storm I: testing regular black holes with LVK and EHT observations
Carlos A. Benavides-Gallego, Swarnim Shashank, Haiguang Xu
According to the celebrated singularity theorems, space-time singularities in general relativity are inevitable. However, it is generally believed that singularities do not exist i…
Gravitational Wave Astronomy With TianQin
En-Kun Li, Shuai Liu, Alejandro Torres-Orjuela +50
The opening of the gravitational wave window has significantly enhanced our capacity to explore the universe's most extreme and dynamic sector. In the mHz frequency range, a divers…
Testing the Kerr nature with binary black hole inspirals
Swarnim Shashank, Cosimo Bambi, Rittick Roy
The theory of general relativity (GR) is the standard framework for the description of gravitation and the geometric structure of spacetime. With the recent advancement of observat…
Modeling reflection spectra of super-Eddington X-ray sources
Swarnim Shashank, Askar B. Abdikamalov, Honghui Liu +5
Relativistic reflection is a common feature in the X-ray observations of accreting compact objects. We present reflux, a new X-ray reflection model for spectral analysis of super-E…
Non-Kerr Constraints using Binary Black Hole inspirals considering phase modifications up to 4 PN order
Debtroy Das, Swarnim Shashank, Cosimo Bambi
The gravitational field around an astrophysical black hole (BH) is thought to be described by the Kerr spacetime, which is a solution of the Einstein equation. Signatures of binary…
X-ray spectra of black hole X-ray binaries with returning radiation
Temurbek Mirzaev, Cosimo Bambi, Askar B. Abdikamalov +4
In the disk-corona model, the X-ray spectrum of a stellar-mass black hole in an X-ray binary is characterized by three components: a thermal component from a thin and cold accretio…
Testing General Relativity with NuSTAR data of Galactic Black Holes : II
Ashutosh Tripathi, Swarnim Shashank, Gitika Mall +1
General relativity predicts the spacetime metric around an astrophysical black hole to be described by the Kerr solution, which is a massive rotating black hole without any residua…
Towards more accurate synthetic reflection spectra: improving the calculations of returning radiation
Temurbek Mirzaev, Shafqat Riaz, Askar B. Abdikamalov +6
We present a new model to calculate reflection spectra of thin accretion disks in Kerr spacetimes. Our model includes the effect of returning radiation, which is the radiation that…
Testing General Relativity with Black Hole X-Ray Data and ABHModels
Cosimo Bambi, Askar B. Abdikamalov, Honghui Liu +3
The past 10 years have seen tremendous progress in our capability of testing General Relativity in the strong field regime with black hole observations. 10 years ago, the theory of…
Testing Regular Black Holes with X-ray data of GX 339-4
Shafqat Riaz, Michail Kyriazis, Askar B. Abdikamalov +2
Regular black holes are singularity-free black hole spacetimes proposed to solve the problem of the presence of spacetime singularities that plagues the black holes of general rela…
Testing relativistic reflection models with GRMHD simulations of accreting black holes
Swarnim Shashank, Shafqat Riaz, Askar B. Abdikamalov +1
X-ray reflection spectroscopy is currently one of the leading techniques for studying the inner part of accretion disks around black holes, measuring black hole spins, and even tes…
Testing regular black holes with X-ray and GW data
Shafqat Riaz, Swarnim Shashank, Rittick Roy +5
The presence of spacetime singularities in physically relevant solutions of the Einstein Equations is normally interpreted as a symptom of the breakdown of classical general relati…
Constraining the Konoplya-Rezzolla-Zhidenko deformation parameters III: limits from stellar-mass black holes using gravitational-wave observations
Swarnim Shashank, Cosimo Bambi
Gravitational-wave observations of binary black holes provide a suitable arena to test the fundamental nature of gravity in the strong-field regime. Using the data of the inspiral…
-mode oscillations of compact stars with realistic equations of state in dynamical spacetime
Swarnim Shashank, Fatemeh Hossein Nouri, Anshu Gupta
In this study, we perform full three dimensional numerical relativity simulations of non-rotating general relativistic stars. Extending the studies for polytropic equation of state…