Black holes and bubbled solutions in String Theory

Giulio Pasini

IPhT

Tue, Sep. 13th 2016, 14:00

Amphi Claude Bloch, Bât. 774, Orme des Merisiers

There exist many smooth solutions in String Theory characterized by a nontrivial topology threaded by fluxes and no localized sources. In this thesis we analyze some of the most important bubbled solutions along with the different purposes they are studied for. Some smooth, eleven-dimensional solutions can be interpreted as BPS black hole microstates in the context of the Fuzzball proposal. One can promote these to be microstates for near-BPS black holes by placing probe supertubes at a metastable minimum inside these solutions. We show that these minima can lower their energy when the bubbles move in certain directions in the moduli space, which implies that these near-BPS microstates are in fact unstable. The decay of these solutions corresponds to Hawking radiation and we compare the emission rate and frequency to those of the corresponding black hole. \par By modifying the asymptotic behavior of these microstates one could be able to construct microstates for five-dimensional BPS black rings with no electric charge. To do so one needs to find a new supergravity solution in five-dimensions whose Killing vector switches from timelike to null in some open regions. We construct explicit examples where the norm of the supersymmetric Killing vector is a real not-everywhere analytic function such that all its derivatives vanish at a point where the Killing vector becomes null. \par In the Lin-Lunin-Maldacena solution we find a supersymmetry-breaking mechanism similar to that used for near-BPS microstates. We analyze the potential energy of M2 probes polarized into M5 brane shells. When the charges of the probe are parallel to those of the solution we find stable configurations, while when the charges are opposite we find metastable states that break supersymmetry and analyze the decay process to supersymmetric configurations ...

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