Executive Summary : | The challenges in fundamental physics, such as dark energy, dark matter, black holes, and big bang singularities, revolve around an unclear understanding of gravity. General Relativity (GR) has been a paradigm that has been successful until some lengthscale, but it must be replaced by a more complete theory that is free from singularities and can be reconciled with quantum mechanics. Alternative gravity models have emerged, including the addition of extra spatial dimensions, higher curvature terms in the gravity Lagrangian, and a combination of these. To test these models against available observations, it is essential to validate, constrain, or falsify them using available astrophysical observations. With increasing data in the electromagnetic domain from advanced missions like NuSTAR, AstroSat, Chandra, and GW observatories like a-LIGO and Virgo, the future prospects for research in this field are bright. Future missions include LIGO-India, KAGRA, Einstein Telescope, LISA, DECIGO, and LOFT. Theoretical modeling of astrophysical observables, such as gravitational waveforms, black hole shadow, and BH continuum spectrum, is necessary for better understanding. This requires analytical calculations and numerical computations, such as generating numerical waveforms in beyond GR models.
This project aims to constrain these models with GW observations and other EM observations, such as QPOs and jets, to verify their mutual consistency. This study can help the scientific community understand the nature of strong gravity, which remains an ill-understood subject. |