General Relativity & Quantum Cosmology

As endpoints of massive stellar evolution, showcases for the densest matter in the universe, and sites for heavy element nucleosynthesis, neutron star mergers are superb laboratories for astrophysics, strong gravity and nuclear physics. Gravitational-wave observations of these mergers are beginning to reveal neutron stars’ internal structure, provide insight into the astrophysical processes that form them, and expose their role in the chemical evolution of the Galaxy. I will survey some of my recent work in these areas and describe how our theoretical understanding of neutron stars is being shaped by gravitational-wave discoveries.

We will explore the connection between Celestial and Euclidean Anti-de Sitter (EAdS) holography in the massive scalar case. Specifically, exploiting the so-called hyperbolic foliation of Minkowski space-time, we will show that each contribution to massive Celestial correlators can be reformulated as a linear combination of contributions to corresponding massive Witten correlators in EAdS. This result will be demonstrated explicitly both for contact diagrams and for the four-point particle exchange diagram, and it extends to all orders in perturbation theory by leveraging the bootstrapping properties of the Celestial CFT (CCFT).  Within this framework, the Kantorovic-Lebedev transform plays a central role, which will be introduced at the end of the talk. This transform will allow us to make broader considerations regarding non-perturbative properties of a CCFT. 

In this talk, I will provide an overview of neutron star (NS) mergers, highlighting the insights gained through numerical relativity simulations. I will mainly focus on the role of the cocoon shock breakout emission as a key early electromagnetic counterpart of NS mergers, with special relevance to events like GW170817. I will explore how the properties of the merger ejecta and the nature of the central engine influence the resulting emission. Additionally, I will present recent advancements in the development of our new general relativistic magnetohydrodynamics (GR-MHD) code GR-Athena++, and share ongoing research efforts on the evolution of magnetic fields in the post-merger remnant.