Current status and prospects of cosmology research in India

Discoveries in cosmology over the last few decades, using multi-band electromagnetic (EM) observations from radio to gamma rays, have shaped our understanding of the Universe and opened a plethora of open questions. The open questions span from the early stages of the Universe, focused on uncovering the physical processes that governed its formation and rapid expansion, to the later evolutionary phases characterized by a transition from dark matter domination to the current epoch dominated by dark energy components that collectively account for \(\sim \)95% of the Universe’s total energy budget. Though their existence is indicated by multiple independent observations, the law of physics, which governs them remains unknown. In the coming years along with multi-band EM observations from telescopes with better sensitivity, an independent cosmological messenger gravitational waves (GW) spanning over nearly 20 decades in frequencies will be able to probe and bring insights to these open questions from the early phase of the Universe till the current stage, and possibly will unveil cosmic mysteries which are currently unknown. These observations will open discovery space in the early epoch of cosmic acceleration known as cosmic inflation, the nature of dark matter, the cosmic evolution of dark energy, the total mass of neutrinos and beyond standard model particle physics. It will also shed light on the cosmic evolution of galaxies, and black holes, and how their interplay has shaped the observable Universe. Furthermore, the area of multi-messenger cosmology by exploring the synergy between GW, EM and neutrino observations will bring to light several uncharted territories in cosmology and fundamental physics. This document provides a summary of the current progress in cosmology and outlines future directions and prospects in the field.