Elisa Maggio
The University of Sheffield (UK)

Abstract
Gravitational-wave astronomy can give us access to structure of black holes, potentially probing microscopic corrections at the horizon scale. Some quantum-gravity models of exotic compact objects replace the event horizon by a reflective surface. Objects with these properties are prone to the so-called ergoregion instability when spinning sufficiently fast.

In this talk I will investigate a model consisting of a Kerr geometry with a reflective surface near the horizon. I will show that the ergoregion instability affects exotic compact objects with a perfectly reflecting surface, and might have a crucial impact on the phenomenology of these objects. On the other hand, I will describe an effect that can prevent the ergoregion instability from developing. A partial absorption at the surface is sufficient to quench the instability completely. This finding has important consequences for the viability of exotic compact objects and it suggests that exotic compact objects are not necessarily ruled out by the ergoregion instability.

2018 March 19, 14:30

IA/U.Lisboa
Faculdade de Ciências da Universidade de Lisboa (C8.6 Meetings Room)
Campo Grande, 1749-016 Lisboa