On the Multiplicity of Single – Centered Extremal Black Holes in Four-dimensional N = 2 Supergravity.
ABSTRACT :
Attractor mechanism provides the macroscopic description of entropy for extremal black holes. As a consequence of this property, the moduli fields of these extremal black holes are fixed at their horizon and are given by the black hole charges irrespective of their asymptotic values. Hence the entropy of these black holes is solely dependent on the black hole charges. However, this is the case only when the moduli space is connected. If the moduli space contains several disjoint branches, black holes possess multiple attractors. The entropy and the attractor solution are unique in each branch. In this talk, I will discuss some examples of multiple attractors with suitable charge configurations in the context of four-dimensional, N=2 supergravity theory coupled to vector multiplets. The case of axionic black holes for which the attractors undergo a phase transition as we change the values of charges across a domain in the charge lattice will also be considered. Besides, I will also discuss the effect of Freudenthal duality on the supersymmetric black holes and the full black hole solution for the same.