A White Paper on The Multi-Messenger Science Landscape in India

TL;DR

This white paper discusses the potential of multi-messenger astronomy in India to explore fundamental physics from neutron star structures to cosmological phenomena, emphasizing observational opportunities across multiple cosmic scales.

Contribution

It highlights the role of Indian observatories in advancing multi-messenger science and identifies key scientific cases and discovery opportunities in this emerging field.

Findings

Multi-messenger observations can probe neutron star properties and matter under extreme conditions.

These observations can address cosmological questions like the Hubble constant, dark matter, and dark energy.

Indian observatories can significantly contribute to global multi-messenger research.

Abstract

The multi-messenger science using different observational windows to the Universe such as Gravitational Waves (GWs), Electromagnetic Waves (EMs), Cosmic Rays (CRs), and Neutrinos offer an opportunity to study from the scale of a neutron star to cosmological scales over a large cosmic time. At the smallest scales, we can explore the structure of the neutron star and the different energetics involved in the transition of a pre-merger neutron star to a post-merger neutron star. This will open up a window to study the properties of matter in extreme conditions and a guaranteed discovery space. On the other hand, at the largest cosmological scales, multi-messenger observations allow us to study the long-standing problems in physical cosmology related to the Hubble constant, dark matter, and dark energy by mapping the expansion history of the Universe using GW sources. Moreover, the multi-messenger studies of astrophysical systems such as white dwarfs, neutron stars, and black holes of different masses, all the way up to a high redshift Universe, will bring insightful understanding into the physical processes associated with them that are inaccessible otherwise. This white paper discusses the key cases in the domain of multi-messenger astronomy and the role of observatories in India which can explore uncharted territories and open discovery spaces in different branches of physics ranging from nuclear physics to astrophysics.