Research

Electromagnetic Detection of Gravitational-Wave Events

I have contributed to the electromagnetic (EM) detection and follow-up of gravitational-wave sources, most notably the first confirmed binary neutron star merger GW170817, which established the field of multi-messenger astronomy. As part of coordinated international campaigns, I was involved in rapid optical and near-infrared observations that identified and monitored the associated kilonova emission AT 2017gfo, linking gravitational-wave signals to their EM counterparts (Abbott et al. 2017). I contributed to follow-up efforts using facilities such as SALT and IRSF, which provided critical constraints on the temporal evolution, ejecta properties, and colour evolution of the kilonova (Buckley et al. 2018; Tominaga et al. 2018). These observations offered direct evidence for r-process nucleosynthesis in neutron star mergers and validated theoretical kilonova models (Kasliwal et al. 2017). This work demonstrated the power of global telescope networks and rapid-response strategies, forming the observational blueprint now used for EM follow-up of events detected by the LIGO–Virgo–KAGRA network.

Diverse Evolutionary Pathways of Nova Explosions

Recent work by my student Chamoli et al. 2025  provides compelling evidence that nova explosions arise from multiple evolutionary pathways, rather than a single, universal scenario. Through a detailed multi-wavelength analysis of the recurrent nova M31N 2017-01e, we demonstrated that this system is best explained as a Be–white dwarf binary, a configuration that lies outside the classical cataclysmic variable framework. This result highlights the critical role of binary architecture, mass-transfer mode, and accretion environment in shaping nova eruptions and their observational signatures. Our work underscores that novae can occur in systems with highly non-standard companions, leading to diverse eruption energetics, recurrence timescales, and spectral evolution. By establishing a clear observational case for an alternative progenitor channel, we have expanded the theoretical parameter space of nova models and reinforced the need for population-based approaches. In the Rubin–LSST era, the discovery of thousands of novae with well-sampled light curves will be essential for identifying such rare evolutionary channels, placing our results in a broader statistical context and enabling a comprehensive census of nova explosion pathways.

Extragalactic Novae in M31

My research on extragalactic novae, with a primary focus on the Andromeda Galaxy (M31), aims to understand the physics of thermonuclear eruptions on accreting white dwarfs, their recurrence behaviour, and their role in binary evolution and Type Ia supernova progenitor pathways. M31 provides a unique laboratory for nova studies, offering a large, well-characterised population at a known distance, enabling systematic, population-level analyses. I have led and contributed to some of the first UV-based surveys of novae in M31 using AstroSat/UVIT, demonstrating that UV observations are crucial for tracing the early and post-maximum phases of nova eruptions and for constraining accretion disk survival and re-formation (Basu et al. 2024; Basu et al. 2025).

A major component of this work has focused on recurrent novae, particularly the remarkable system M31N 2008-12a, where multi-epoch UV and optical observations reveal repeated eruptions on timescales of months to a year, placing stringent constraints on white dwarf mass growth and mass retention efficiency (Basu et al. 2024). I have also been involved in coordinated optical spectroscopic and photometric follow-up of novae in M31, combining data from GROWTH-India Telescope (GIT) and other facilities to classify eruptions and characterise their temporal evolution.

My research vision is to exploit LSST’s high-cadence, wide-field optical monitoring to build an unprecedented, homogeneous nova sample in M31, capturing early-rise, peak, and decline phases for thousands of events. When combined with targeted UV follow-up and archival mining, this approach will enable statistically robust tests of nova population models, eruption physics, and recurrence rates, firmly establishing extragalactic novae as key time-domain laboratories.

Tracing galaxy transformation from extended tidal debris to complex nuclei

My research on galaxy interactions and mergers aims to understand how gravitational encounters transform galaxies across all spatial scales, from extended tidal debris and polar structures to dynamically complex nuclear regions. Using a combination of UV, optical, and near-infrared imaging together with integral-field spectroscopy, I study how interactions redistribute mass and angular momentum, trigger star formation, and restructure galaxy centres. A key component of this work has been the systematic identification and classification of faint tidal features and merger remnants in nearby early-type galaxies, demonstrating that many apparently relaxed systems retain clear signatures of recent or ongoing interactions (Giri, Barway & Raychaudhury 2023).

I have also explored extreme interaction-driven morphologies, including long tidal tails and the formation of tidal dwarf and ultra-diffuse systems at their termini, highlighting how interactions can give rise to new stellar systems far from galaxy centres (Watts et al. 2024). In parallel, my work on polar ring and polar disk galaxies uses deep imaging and kinematic information to probe the role of external accretion and minor mergers in building misaligned structures and sustaining star formation in otherwise quiescent hosts.

At nuclear scales, my IFU-based studies reveal that interactions and mergers frequently produce kinematically distinct components, nuclear disks, and disturbed central regions, linking large-scale encounters to internal dynamical restructuring (Mondal & Barway 2024; Keshri et al. 2025). Recent work on triple AGN systems further demonstrates how repeated interactions in compact environments can profoundly influence nuclear structure and black hole growth (Kesari et al. 2025).

I want to exploit JWST NIRCam’s sensitivity to low-surface-brightness tidal tails, polar structures, and embedded nuclear components, together with MIRI’s ability to trace dust-obscured star formation and shocked interstellar media in merger-driven environments. Combined with IFU surveys such as MaNGA and deep, wide-field imaging from Rubin–LSST, this approach will enable a unified view of how interactions and mergers reshape galaxies from their outskirts to their nuclei.

Laboratories for Extreme Star Formation, Dynamics, and Disk evolution

Collisional ring galaxies provide some of the clearest observational evidence of impulsive gravitational interactions, offering unique laboratories to study density-wave–driven star formation, disk response to perturbations, and secular restructuring following a collision. My research on collisional ring systems combines UV, optical, near-infrared imaging, and integral-field spectroscopy to trace the interplay between stellar populations, gas dynamics, and structural evolution. A major focus of this work has been the Cartwheel galaxy, where I demonstrated the presence of a previously undetected near-infrared bar and pseudo-bulge, revealing that strong internal structures can survive or be rebuilt after violent collisions (Barway et al. 2020).

Using AstroSat/UVIT, I have explored the spatially resolved star formation histories of collisional rings, showing that UV emission traces outwardly propagating star formation fronts and highlights age gradients across the ring (Mayya et al. 2024). Complementary MUSE IFU studies of collisional ring systems have revealed complex kinematics in their central regions, including evidence for kinematically distinct components and bar–ring coupling, emphasising that these galaxies are dynamically far from equilibrium (Mondal & Barway 2024; Mondal & Barway 2025).

Using JWST, I aim to exploit NIRCam’s sensitivity to faint stellar structures and post-collisional disks, alongside MIRI’s ability to probe dust-obscured star formation and shocked interstellar medium within expanding rings. Combined with UVIT, MUSE, and future Rubin–LSST time-domain imaging, this multi-wavelength approach will place collisional ring galaxies in a unified evolutionary framework, linking impulsive interactions to long-term disk and bulge evolution.

Tracing Black Hole Growth through Galaxy structure, environment, and multi-wavelength diagnostics

My research on supermassive black holes (SMBHs) and active galactic nuclei (AGN) focuses on understanding how black hole growth is regulated by galaxy structure, interactions, and environment, and how AGN activity feeds back into galaxy evolution. A recurring theme of my work is that AGN triggering is not exclusively merger-driven, but often arises from a complex interplay between secular processes, bars, tidal interactions, and group environments. Through optical and near-infrared structural analysis, I have investigated the bulge properties of AGN host galaxies, showing that both classical bulges and pseudo-bulges can host actively accreting SMBHs, challenging simple co-evolution prescriptions (Barway & Kembhavi 2007; Barway et al. 2016).

A significant component of my recent work has concentrated on dual and multiple AGN systems, which provide direct observational evidence for hierarchical galaxy growth. Using multi-wavelength observations and integral-field spectroscopy, I have contributed to the identification and characterisation of dual and triple AGN in interacting galaxy groups, revealing disturbed kinematics, enhanced central activity, and the critical role of galaxy interactions in driving gas inflows (Yadav et al. 2021; Nehal et al. 2025).

In the JWST era, my research aims to exploit NIRCam’s sensitivity to faint nuclear structures, bars, and stellar mass distributions, together with MIRI’s unique capability to probe dust-obscured AGN activity and circumnuclear star formation, to uncover obscured or low-luminosity AGN missed at optical wavelengths. Combined with IFU surveys such as MaNGA and deep imaging from Rubin–LSST, this approach will enable a physically motivated census of SMBH growth across environments, firmly linking black hole accretion to galaxy structure and evolutionary stage.

Lenticular (S0) Galaxies are not the end of Galaxy Evolution — They are its most revealing test cases

Lenticular (S0) galaxies are often mischaracterised as passively quenched remnants of spirals, yet my research demonstrates that they are among the most structurally and evolutionarily complex systems in the nearby Universe. Using UV–optical–NIR observations, I have shown that S0 galaxies host a wide diversity of bulge types, including a substantial population of pseudo-bulges, directly challenging the classical merger-dominated paradigm (Barway et al. 2007; Barway et al. 2009). UV studies combining GALEX with optical and infrared data revealed a strong luminosity dependence in S0 star-formation histories, with low-mass systems frequently showing extended or rejuvenated star formation, while massive S0s are largely quiescent (Barway et al. 2013). Contrary to the notion that bars are fossil structures in S0s, my work demonstrates that bars remain dynamically important, driving secular evolution, central rejuvenation, and bulge growth even at late times (Barway et al. 2011; Barway et al. 2016; Barway & Saha 2020). Environmental studies further indicate that galaxy groups, not clusters alone, are key sites of S0 transformation, where tidal interactions and secular processes operate in tandem (Mishra, Wadadekar & Barway 2017). In the JWST, MaNGA, and Rubin–LSST era, my research vision is to combine IFU kinematics with deep UV imaging, JWST/NIRCam mapping of faint stellar structures, and JWST/MIRI constraints on dust-obscured star formation and evolved stellar populations, alongside machine-learning based morphological analysis, to link stellar populations, dynamics, and low-surface-brightness tidal features moving decisively beyond simplistic faded spiral models and positioning S0 galaxies as critical laboratories for galaxy evolution.