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SUMMARY:Calm after the storm: black hole ringdown beyond linear perturbati
 on theory.  - Laura Sberna\, AEI Potsdam
DTSTART:20210618T120000Z
DTEND:20210618T130000Z
UID:TALK159409@talks.cam.ac.uk
CONTACT:Chandrima Ganguly
DESCRIPTION:Recent analyses have shown that the gravitational-wave signal 
 emitted by merging black holes is surprisingly simple in its final stages.
  It has long been known that the very end stage of a black hole merger—t
 he late ringdown—is well-described by black hole perturbation theory. Th
 e latter\, however\, has been found to be in excellent agreement with nume
 rical simulations even at much earlier times\, immediately following the m
 erger. In this talk\, I will describe efforts to understand this phenomeno
 n by characterizing the size and nature of backreaction effects in black-h
 ole ringdowns. Our analysis\, which we validate against numerical relativi
 ty simulations\, is based on a novel perturbation theory incorporating a b
 ilinear form between quasinormal modes. From a toy-model system (an asympt
 otically anti-de Sitter black hole with a ringing scalar field)\, to gravi
 tational perturbations of Schwarzschild\, the lessons we learn can help ex
 plain the simplicity of ringdown signals. I will also discuss ongoing effo
 rts to extend these studies to more realistic (Kerr) black holes.\n
LOCATION:Zoom
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