4 papers
Taming the Aretakis instability: extremal black holes with multi-degenerate horizons
Shreyansh Agrawal, Panagiotis Charalambous, Laura Donnay +2
Stationary black hole geometries with non-degenerate Cauchy horizons are classically unstable due to mass inflation. At extremality, mass inflation is absent, but a different dynam…
Null infinity as an inverted extremal horizon: Matching an infinite set of conserved quantities for gravitational perturbations
Shreyansh Agrawal, Panagiotis Charalambous, Laura Donnay
Every spacetime that is asymptotically flat near null infinity can be conformally mapped via a spatial inversion onto the geometry around an extremal, non-rotating and non-expandin…
Soft theorems and spontaneous symmetry breaking
Shreyansh Agrawal, Kevin Nguyen
The soft photon and soft graviton theorems of Weinberg are known to derive from conservation laws associated with asymptotic symmetries. Within the corresponding classical theories…
Celestial algebra in Einstein-Yang-Mills theory
Shreyansh Agrawal, Panagiotis Charalambous, Laura Donnay
From a study of the subleading structure of the asymptotic equations of motion in Einstein-Yang-Mills theory, we construct charges that are conserved up to quadratic order in non-r…