arXiv subjects

Gavin S. Hartnett

Publications and source records attributed to Gavin S. Hartnett.

25 records · Page 2Linked to original sources

arXiv2017

Mass-deformed M2 branes in Stenzel space

We obtain finite-temperature M2 black branes in 11-dimensional supergravity, in a $G_4$-flux background whose self-dual part approaches a solution of Cvetič, Gibbons, Lü, and Pope, based upon Stenzel's family of Ricci-flat Kähler deformed cones. Our solutions are asymptotically $AdS_4$ times a 7-dimensional Stiefel manifold $V_{5,2}$, and the branes are ``smeared'' to retain $SO(5)$ symmetry in the internal space. The solutions represent a mass deformation of the corresponding dual $CFT_3$, whose full description is at this time only partially-understood. We investigate the possibility of a confinement/de-confinement phase transition analogous to the $AdS_5 \times S^5$ case, and a possible Gregory-Laflamme type instability which could lead to polarised brane solutions which break $SO(5)$. We discuss possible consequences for AdS/CFT and the KKLT cosmological uplift mechanism.

hep-th↗

arXiv2015

Localised Anti-Branes in Flux Backgrounds

Solutions corresponding to finite temperature (anti)-D3 and M2 branes localised in flux backgrounds are constructed in a linear approximation. The flux backgrounds considered are toy models for the IR of the Klebanov-Strassler solution and its M-theory analogue, the Cvetič-Gibbons-Lü-Pope solution. Smooth solutions exist for either sign charge, in stark contrast with the previously considered case of smeared black branes. That the singularities of the anti-branes in the zero temperature extremal limit can be shielded behind a finite temperature horizon indicates that the singularities are physical and resolvable by string theory. As the charge of the branes grows large and negative, the flux at the horizon increases without bound and diverges in the extremal limit, which suggests a resolution via brane polarisation à la Polchinski-Strassler. It therefore appears that the anti-brane singularities do not indicate a problem with the SUSY-breaking metastable states corresponding to expanded anti-brane configurations in these backgrounds, nor with the use of these states in constructing the de Sitter landscape.

hep-th↗

arXiv2014

A No Black Hole Theorem

We show that one cannot put a stationary (extended) black hole inside certain gravitating flux-tubes. This includes an electric flux-tube in five-dimensional Einstein-Maxwell theory, as well as the standard flux-branes of string theory. The flux always causes the black hole to grow indefinitely. One finds a similar restriction in a Kaluza-Klein setting where the higher dimensional spacetime contains no matter.

hep-th↗

arXiv2014

Quasinormal modes of asymptotically flat rotating black holes

We study the main properties of general linear perturbations of rotating black holes in asymptotically flat higher-dimensional spacetimes. In particular, we determine the quasinormal mode (QNM) spectrum of singly spinning and equal angular momenta Myers-Perry black holes (MP BHs). Emphasis is also given to the timescale of the ultraspinning and bar-mode instabilities in these two families of MP BHs. For the bar-mode instabilities in the singly spinning MP BH, we find excellent agreement with our linear analysis and the non-linear time evolution of Shibata and Yoshino for d=6,7 spacetime dimensions. We find that d=5 singly spinning BHs are linearly stable. In the context of studying general relativity in the large dimension limit, we obtain the QNM spectrum of Schwarzschild BHs and rotating MP BHs for large dimensions. We identify two classes of modes. For large dimensions, we find that in the limit of zero rotation, unstable modes of the MP BHs connect to a class of Schwarzschild QNMs that saturate to finite values.

hep-th↗

arXiv2013

Holographic thermalization, quasinormal modes and superradiance in Kerr-AdS

Black holes in anti-de Sitter (AdS) backgrounds play a pivotal role in the gauge/gravity duality where they determine, among other things, the approach to equilibrium of the dual field theory. We undertake a detailed analysis of perturbed Kerr-AdS black holes in four- and five-dimensional spacetimes, including the computation of its quasinormal modes, hydrodynamic modes and superradiantly unstable modes. Our results shed light on the possibility of new black hole phases with a single Killing field, possible new holographic phenomena and phases in the presence of a rotating chemical potential, and close a crucial gap in our understanding of linearized perturbations of black holes in anti-de Sitter scenarios.

hep-th↗

arXiv2013

Non-Axisymmetric Instability of Rotating Black Holes in Higher Dimensions

We calculate the scalar-gravitational quasi-normal modes of equal angular momenta Myers-Perry black holes in odd dimensions. We find a new bar-mode (non-axisymmetric) classical instability for $D \ge 7$. These black holes were previously found to be unstable to axisymmetric perturbations for spins very near extremality. The bar-mode instability we find sets in at much slower spins, and is therefore the dominant instability of these black holes. This instability has important consequences for the phase diagram of black holes in higher dimensions.

gr-qc↗

arXiv2012

Geons and Spin-2 Condensates in the AdS Soliton

We construct geons starting with gravitational perturbations of the AdS soliton. Previous studies of a charged scalar field in the soliton background showed a holographic insulator/superconductor transition at a critical chemical potential. We explore the possibility that dimensional reduction of the geon could model a transition to a d-wave superconductor. We find that although one does get a charged spin-2 condensate, it has higher free energy than the state without the condensate, so there is no phase transition.

hep-th↗