International Centre for Theoretical Sciences — TIFR

Ruchi Mishra compares magnetized accretion onto charged black holes and horizonless compact objects using ongoing three-dimensional general-relativistic magnetohydrodynamic simulations. In a Reissner–Nordström spacetime whose charge exceeds its mass, a naked singularity replaces the event horizon, with a repulsive region, a zero-gravity radius, and a different structure of circular orbits. Earlier equilibrium calculations found toroidal rotating-fluid configurations around such singularities. Building on that work, the simulations examine how charge changes the accumulation of matter, transport of angular momentum, and organization of magnetic fields.

Aditya Dwarkesh explains how geometric quantization extends from ordinary symplectic geometry to higher stacks represented by simplicial manifolds. Whereas ordinary prequantization produces line bundles, the shifted setting leads to bundle gerbes, higher-categorical analogues of principal bundles. For a compact simple Lie group G, the string group provides an example of a multiplicative bundle gerbe over G and can be understood through prequantization of BG with a 2-shifted symplectic structure. The talk develops this relationship and may include a sketch of a new model for String(G).