Black hole mimickers in string theory

by Suvendu Giri (Milano Bicocca U.)

Wednesday 23 Nov 2022, 15:00 → 16:00 Europe/Rome

1/1-2 - Aula "C. Voci" (Dipartimento di Fisica e Astronomia - Edificio Marzolo)

In this talk I will argue that “black shells”, which are spherical brane bubbles enclosing AdS spacetime can mimic black holes. Such bubbles of AdS in an asymptotically flat spacetime are generically unstable, but can be stabilized at a finite radius outside the would-be horizon of the corresponding object by additional matter arising from dissolved D0-anti D0 branes and a gas of open strings. These bubbles can arise from brane polarization à la Myers’ effect, and are natural to expect from string theory. After illustrating key features of black shells that mimic a Schwarzschild black hole, I will describe how the construction can be extended to slowly rotating black shells that mimic a Kerr black hole. Remarkably, these possess a distinct observational signature in the form of an independent quadrupole moment. This can be detected in astrophysical observations like LIGO, and could provide a way to rule out, confirm or refine these objects as viable alternatives to black holes in our universe. I will then talk about recent progress on the stability of these objects, and highlight a highly non-trivial result that warrants further study. I will highlight a natural line of investigation that this opens up, and is related to recovering the exact form of the energy flux from string theory. In the end, I will also provide a teaser of an ongoing computation of the “shadow” of these objects that could be detectable by direct imaging experiments like the Event Horizon Telescope (EHT).