Research Outputs (School of Physics)

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Browsing Research Outputs (School of Physics) by Keyword "Black Holes in String Theory"

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    Heating up branes in gauged supergravity
    (Springer, 2014-08-26) Goldstein, Kevin; Nampuri, Suresh; V´eliz-Osorio, Alvaro
    In this note, we explore the solution space of non-extremal black objects in 4D and 5D N = 2 gauged supergravity in the presence of fluxes. We present first order rewritings of the 4D action for a classes of non-extremal dyonic and electric solutions with electric flux backgrounds. Additionally, we obtain the non-extremal version of the Nernst brane in AdS 5 using a simple deformation. Finally, we develop a new technique to deform extremal black solutions in 4D to non-extremal solutions by an analysis of the symmetries of the equations of motion.
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    The hot attractor mechanism: decoupling without deep throats
    (Springer Verlag, 2016-04) Goldstein, K.; Jejjala, V.; Nampuri, S.
    Non-extremal black holes in (Formula presented.) supergravity have two horizons, the geometric mean of whose areas recovers the horizon area of the extremal black hole obtained from taking a smooth zero temperature limit. In prior work [1] using the attractor mechanism, we deduced the existence of several moduli independent invariant quantities obtained from averaging over a decoupled inter-horizon region. We establish that non-extremal geometries at the Reissner-Nordström point, where the scalar moduli are held fixed, can be lifted to solutions in supergravity with a near-horizon AdS3×S2. These solutions have the same entropy and temperature as the original black hole and therefore allow an interpretation of the underlying gravitational degrees of freedom in terms of CFT2. Symmetries of the moduli space enable us to explicate the origin of entropy in the extremal limit.
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    Indefinite theta functions for counting attractor backgrounds
    (Springer, 2014-10-03) Cardoso, Gabriel Lopes; Ciraficia, Michele; Nampurib, Suresh
    In this note, we employ indefinite theta functions to regularize canonical partition functions for single-center dyonic BPS black holes. These partition functions count dyonic degeneracies in the Hilbert space of four-dimensional toroidally compactified heterotic string theory, graded by electric and magnetic charges. The regularization is achieved by viewing the weighted sums of degeneracies as sums over charge excitations in the near-horizon attractor geometry of an arbitrarily chosen black hole background, and eliminating the unstable modes. This enables us to rewrite these sums in terms of indefinite theta functions. Background independence is then implemented by using the transformation property of indefinite theta functions under elliptic transformations, while modular transformations are used to make contact with semi-classical results in supergravity.