Gravitational waves (GWs) from the inspiral of binary compact objects offer a one-step measurement of the luminosity distance to the event, which is essential for the measurement of the Hubble constant, H0, which characterizes the expansion rate of the Universe. However, unlike binary neutron stars, the inspiral of binary black holes is not expected to be accompanied by electromagnetic radiation and a subsequent determination of its redshift. Consequently, independent redshift measurements of such GW events are necessary to measure H0. I will present how one can use statistical techniques such as cross-correlation between GW events and galaxies to infer the Hubble constant. I will present curated galaxy catalogs from the photometric data from the DESI Imaging legacy surveys for this purpose. Finally, I will also discuss a new Bayesian approach to infer H0 by measuring the overdensity of galaxies around individual binary black hole merger events in configuration space and the current precision of such measurements of the Hubble constant.
Prof. Surhud More is a Professor of Astronomy at the Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune, India, whose research spans cosmology, galaxy formation and evolution, and the outskirts of the Solar System. He obtained his Ph.D. from the Max Planck Institute for Astronomy in Heidelberg and pursued postdoctoral research at the University of Chicago. Before joining IUCAA in 2018, he was an Associate Professor at the Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo. Prof. More serves on the Science Advisory Committee of the Thirty Meter Telescope, one of India’s major mega-science projects, and plays a key leadership role in international collaborations as the Program Manager for the Rubin Legacy Survey of Space and Time (LSST) at IUCAA. He also serves as the Deputy Manager of the Office of Astronomy for Education (OAE) Center India and the National Astronomy Education Coordinator for India. Actively engaged in astronomy education and outreach, he has guided several Indian Astronomy Olympiad teams and contributed to the development of the latest NCERT school textbooks. In recognition of his outstanding scientific and educational contributions, Prof. Surhud More has been awarded the Vigyan Yuva–2025 Award by the Government of India.