Excitation of Ringdown Direct Waves

          @misc{ scivideos_PIRSA:26040063,
            doi = {10.48660/26040063},
            url = {https://pirsa.org/26040063},
            author = {Ma, Sizheng},
            keywords = {Cosmology},
            language = {en},
            title = {Excitation of Ringdown Direct Waves},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2026},
            month = {apr},
            note = {PIRSA:26040063 see, \url{https://scivideos.org/pirsa/26040063}}
          }
          

Abstract

It has recently been argued that the merger phase of gravitational waves from binary black hole coalescences contains not only quasinormal modes but also a newly identified component, the so-called “direct wave”. As the “last scream” of two merging black holes before they are silenced by the remnant, this component exhibits a characteristic oscillation and decay pattern controlled by two fundamental properties of the final horizon: its rotation frequency and surface gravity. In this talk, I will present a general physical picture of the direct wave: what it is, how it arises, and how it can be extracted from numerical-relativity simulations and from the loudest observed event, GW250114. I will further discuss how this component can serve as a new probe of horizon dynamics.