Relativity Seminar with Tousif Islam

Abstract: With nearly 200 binary black hole mergers detected to date, gravitational-wave (GW) astronomy is rapidly transforming our understanding of astrophysics, including star-formation histories, binary formation channels, the neutron star–black hole mass gap, and the role of pair-instability supernovae. Extracting this information from GW observations crucially depends on accurate and efficient models of gravitational radiation and merger remnants. In this talk, I will present my approach to waveform and remnant modeling that combines the strengths of multiple theoretical and computational frameworks. This approach leverages the efficiency of reduced-order surrogate modeling, the physical transparency of phenomenological models, insights from post-Newtonian theory, and the power of state-of-the-art machine-learning techniques. It further integrates numerical-relativity simulations from multiple groups, together with information from black-hole perturbation theory and second-order self-force calculations, into a unified multi-fidelity modeling framework. I will focus in particular on a class of models I am developing under the umbrella of gwModels, which aim to bring these diverse ingredients together. Finally, I will highlight how these models, alongside other surrogate approaches, are enabling new astrophysical insights.