Cosmology with multi-messenger transients

Astrophysical transients like Supernovae (SNe), Superluminous Supernovae (SLSN), Gamma Ray Bursts , Kilonovae, and gravitational-wave signals from neutron stars (NS) and black holes (BH) carry enormous amounts of energy and can be seen up to high redshifts. The coming decade(s) will see an exemplary combination of next-generation, ground-based (such as Einstein Telescope and Cosmic Explorer) and space-borne (LISA) detectors reaching unprecedented sensitivities in detecting gravitational waves (GW). This will be complemented with advanced future telescopes (e.g. VRO, SKA, CTA) to search for GW counterparts and other fainter transients across the EM spectrum, which will allow us to observe a larger number of these events and to reach larger distances.

We aim to explore such transients for exploring their potential as distance indicators at different scales. If standardizable, these transients will be valuable tools to measure precise distances and independently constrain the Hubble parameter, which is crucial for resolving the Hubble tension. As part of this effort, we have shown in a novel approach the use of surface brightness fluctuations (SBF) distance measures for calibrating SNe Ia luminosity and constraining the value of the Hubble constant. This work also examined the effect of host galaxy types on Ia luminosity and the H0 value. The results from this work have important implications for the 'Hubble tension' problem. We are also exploring comparatively rare transients like superluminous supernovae and kilonovae for their use as cosmological probes at high and low redshifts, respectively. Additionally, as a collaboration with the cosmology group of LVC, we will be contributing in the efforts towards using gravitational waves as standard sirens.