Talks

The remnant of a binary black hole coalescence is a perturbed black hole, which equilibrates by emitting ringdown gravitational waves. These ringdown waves not only encode information in their frequencies about the spacetime structure of the remnant black hole metric, but also have imprints in their amplitudes of the progenitor black hole binary's properties. In this talk I will highlight recent results in black hole ringdown data analysis and new understanding of astrophysical ringdown amplitudes gleaned from numerical relativity simulations, and will then discuss how ringdown analyses may become a vital tool for making inferences of binary black hole properties - even in situations where the gravitational wave signal from the binary inspiral itself is never directly observed.

The Virasoro conformal blocks are very interesting since they have many connections to other areas of math and physics. For example, when $c=1$, they are related to tau functions of integrable systems of Painlev\'{e} equations. They are also closely related to non-perturbative completions in the topological string theories. I will first explain what Virasoro conformal blocks are. Then I will describe a new way to construct Virasoro blocks at $c=1$ on $C$ by using the "abelian" Heisenberg conformal blocks on a branched double cover of C. The main new idea in our work is to use a spectral network and I will show the advantages of this construction. This nonabelianization construction enables us to compute the harder-to-get Virasoro blocks using the simpler abelian objects. It is closely related to the idea of nonabelianization of the flat connections in the work of Gaiotto-Moore-Neitzke and Neitzke-Hollands. This is based on a joint work with Andrew Neitzke.