Research

My research explores several areas in gravitational physics. My current interests lie in gravitational wave astronomy. Below is a list of my research activities.

Defining eccentricity for GW astronomy

Defines a standard framework for measuring eccentricity in gravitational wave (GW) astronomy, along with methods to calculate eccentricity directly from gravitational waveforms.

Papers: arXiv:2302.11257, arXiv:2507.08345, arXiv:2503.19538

Collaborators: Vijay Varma, Antoni Ramos Buades, Harald Pfeiffer, Michael Boyle, Mark A. Scheel, Larry Kidder

In General Theory of Relativity, there is no unique way to define the eccentricity of a binary system's orbit. This can lead to ambiguity about the binary's eccentricity inferred from GW observations. In our works, we propose a standardized definion that relies solely on the gravitational waveforms, removing gauge ambiguity and model dependence. This standardized definion can be used to measure eccentricity from gravitational waveform emitted by binaries on generic bound orbits.

A Python implementation of the method is available on GitHub: gw_eccentricity.

Test of General Relativity using GWs

The Inspiral-Merger-Ringdown Consistency Test (IMRCT) is a key tool for testing the validity of General Relativity (GR) using gravitational waves (GWs) emitted by compact binary systems. We extend this test to GW signals from eccentric binaries.

Papers: arXiv:2402.15110

Collaborators: Shasvath Kapadia

IMRCT meets eccentricity

The IMRCT is usually peformed using quasicircular template which assumes the binary's orbit to be circular. We first show that using quasicircular template for IMRCT on eccentric signals may lead to false violation of GR. We then show that when the IMRCT is peformed using eccentric template such spurious violation of GR goes away. This emphasises the need for using eccentric templates when analysing GW data and peforming test of GR using GW observations.

Gravitational Lensing of GWs

We build fast and accurate surrogate model of microlensed gravitational wave, and probe nature of the lens using gravitational wave observations.

Papers: arXiv:2401.06553, arXiv:2501.02974

Collaborators: Uddeepta Deka, Shasvath Kapadia, Parameswaran Ajith, Vijay Varma, Scott Field

Fast and accurate microlensing template via surrogate modeling

This study focuses on modeling the gravitational microlensing effect on gravitational waves (GWs) produced by different lens configurations.

The microlensing effect is computed via a numerically expensive integration, making the generation of templates required for gravitational wave (GW) data analysis prohibitive. We circumvent this challenge by applying surrogate modeling techniques. The surrogate model enables fast and accurate generation of microlensed GW templates, making parameter estimation from GW observations feasible.

Probing the nature of black holes using microlensing of GWs

The research highlights the potential of gravitational wave microlensing as a tool to probe the properties and nature of the lens, offering new insights into the nature of the lens black hole.

Early warning with GW higher modes

Papers: arXiv:2005.08830, arXiv:2010.12407, arXiv:2012.03963, arXiv:2202.05802

Collaborators: Shasvath Kapadia, Mukesh Kumar Singh, Parameswaran Ajith

Black hole accretion and analogue gravity

Papers: arXiv:1612.07963, arXiv:1612.07954, arXiv:1705.04918, arXiv:1803.09896, arXiv:1806.04084, arXiv:2106.07598

Collaborators: Tapas Kumar Das, Pratik Tarafdar