Line-intensity mapping (LIM) is a promising tool for probing large cosmological volumes and studying galaxy clustering. While point-source detections with facilities such as ALMA and JWST are capable of providing detailed constraints on individual galaxies, galaxy LIM surveys complement it by detecting bright emission lines from galaxies like [C II]_\(158\mu\)m, CO, [O III]_\(88\mu\)m, Ly-\(\alpha\), on a low-resolution map over large-scales. It does so by accumulating the aggregate flux of line emissions from numerous sources, thereby capturing the contribution from both the bright and faint galaxies within a low-resolution voxel. These line emissions are tracers of various astrophysical processes within galaxies e.g. star-formation. With the advent of instruments like CONCERTO, TIME, FYST, COMAP, SPHEREx, CDIM, etc., we will be able to study galaxy evolution, their properties and how they drove cosmic reionization, among many other scientific goals (for a review, head to Kovetz et al. 2022, doi:10.1007/s00159-022-00143-0, arXiv:2206.15377; Murmu et al. 2022, doi:10.1007/s12036-022-09882-z, arXiv:2210.09612).

Similarly, mapping the evolution of the IGM over cosmic times by tracing the [H I]_21cm signal from neutral hydrogen gas using radio interferometers such as uGMRT, LOFAR, HERA, MWA, and the upcoming SKA can give us a complementary perspective on how cosmic reionization happened and how hydrogen gas is bound in galaxies during the post-Epoch of Reionization Era. I use a combination of N-body and semi-numerical simulations of cosmic reionization to model these various kinds of line emissions and make mock forecasts relevant to these instruments. I also do cross-correlation studies between these multiple line-emission tracers, and I am interested in galaxy surveys with BOSS/eBOSS, DESI, HETDEX, JWST, ALMA and possible synergy studies with various LIM missions.