Research

I employ analytic, semi-analytic and numerical techniques to address problems arising in gravitational wave physics. Below I provide details on some topics that I have worked recently. 

Project 1: Gravitational wave memory in cosmology

Memory effects have been extensively studied in asymptotically flat spacetimes due to their deep connections with asymptotic symmetries and soft theorems. However, this focus has limited the exploration of memory in broader settings—particularly in cosmological spacetimes. In our recent work, we bridge this gap by formulating a master equation for Locally Rotationally Symmetric (LRS) spacetimes.

When applied to FLRW geometries, our framework uncovers a novel integrated signal—termed integrated cosmological memory—that is potentially detectable at high redshifts. This opens the exciting possibility of probing cosmological models using gravitational waves alone, without relying on electromagnetic counterparts. Future-generation detectors such as the Einstein Telescope and Cosmic Explorer could be instrumental in observing this signal. Our formalism also naturally captures the transition redshift marking the shift from a matter-dominated to a dark energy-dominated universe—providing an independent test of cosmic expansion history.

Building on this, we further explored the implications of our framework within the context of parity-violating theories of gravity, specifically dynamical Chern-Simons gravity. This extension offers insights into how persistent GW observables could signal violations of general relativity. This work received an Honorable Mention in the Gravity Research Foundation Essay Competition 2025 and has been accepted for publication in Physical Review D Letters.

Project 2: Self-interaction in supernova neutrinos

Gravitational memory signal coming out of supernova neutrinos has been well-studied in the literature. In such dense environments, it is predicted that neutrinos cannot free-stream and instead should undergo self-interaction. However, no such signals of self-interaction was studied in the context of GWs. 

To fill this void, we  explicitly worked out how the self-interaction modifies the GW memory signal if one incorporates its effects on the escaping neutrinos. The self-interaction gets incorporated in the velocity profile of the neutrinos. We could show that neutrino self-interactions can be captured from  future GW detectors like DECIGO and BBO.  This work was published in Physical Review D letters. 

Project 3: Probing modified gravity using binary systems

Ever since the discovery of the first binary pulsar by Hulse and Taylor in 1974, it became possible to test relativistic gravity by examining how gravitational-wave backreaction affects the orbital evolution of such systems. In particular, the secular decay of the orbital period provides a powerful probe, as different theories of gravity predict different rates of orbital energy loss.

In our work, we investigate this problem within the framework of Unimodular Gravity. Using a semi-classical approach, we compute the gravitational-wave energy loss from a binary system and derive the corresponding orbital period decay. This allows us to place constraints on unimodular gravity. Remarkably, we find that our constraint is an order of magnitude stronger than an existing, equivalent bound derived from neutron-star tidal deformability.

Project 4: Qunatum entanglement meets gravitational waves

It has been shown that periodic GWs cause vacuum entanglement. We studied how linearized GW bursts affect entanglement harvesting between static Unruh-DeWitt detectors, considering bursts with and without memory. Our results, published in Journal of High Energy Physics, show that with memory, entanglement increases with decreasing transition energy, while without memory, it stabilizes, linking this behavior to Weinberg's leading term in soft-graviton theorem studies.

In another work, we explore how GW bursts, with or without memory, affect radiative transitions in entangled quantum probes modeled as two-level atomic systems. Our findings, published in here, demonstrate that the collective transitions of these entangled probes are affected solely by the memory component of the GW burst. The methodology developed has potential applications in detecting memory effects using atomic detectors.