Probing the hydrodynamic limit of (super)gravity

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We present a general treatment of the leading order dynamics of the collective modes of charged dilatonic p-brane solutions of (super)gravity theories in arbitrary backgrounds. To this end we employ the general strategy of the blackfold approach which is based on a long-wavelength derivative expansion around an exact or approximate solution of the (super)gravity equations of motion. The resulting collective mode equations are formulated as forced hydrodynamic equations on dynamically embedded hypersurfaces. We derive them in full generality (including all possible asymptotic fluxes and dilaton profiles) in a far-zone analysis of the (super)gravity equations and in representative examples in a near-zone analysis. An independent treatment based on the study of external couplings in hydrostatic partition functions is also presented. Special emphasis is given to the forced collective mode equations that arise in type IIA/B and eleven-dimensional supergravities, where besides the standard Lorentz force couplings our analysis reveals additional couplings to the background, including terms that arise from Chern-Simons interactions. We also present a general overview of the blackfold approach and some of the key conceptual issues that arise when applied to arbitrary backgrounds.

Section: Jhep10(2016)154mentioning

confidence: 99%

Section: Jhep10(2016)154mentioning

confidence: 99%

Section: External Couplings From Hydrostatic Partition Functionsmentioning

confidence: 99%

Section: External Couplings From Hydrostatic Partition Functionsmentioning

confidence: 99%

Section: Jhep10(2016)154mentioning

confidence: 99%

See 3 more Smart Citations

Forced fluid dynamics from blackfolds in general supergravity backgrounds

Armas

Gath

Niarchos

et al. 2016

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Chiral vortical effect from the compactified D4-branes with smeared D0-brane charge

Chen

Huang

2017

By using the boundary derivative expansion formalism of fluid/gravity correspondence, we study the chiral vortical effect from the compactified D4-branes with smeared D0-brane charge. This background corresponds to a strongly coupled, nonconformal relativistic fluid with a conserved vector current. The presence of the chiral vortical effect is induced by the addition of a Chern-Simons term in the bulk action. Except that the non-dissipative anomalous viscous coefficient and the sound speed rely only on the chemical potential, most of the other thermal and hydrodynamical quantities of the first order depend both on the temperature and the chemical potential. According to our result, the way that the chiral vortical effect coefficient depends on the chemical potential seems irrelevant with whether the relativistic fluid is conformal or not. Stability analysis shows that this anomalous relativistic fluid is stable and the doping of the smeared D0-brane charge will slow down the sound speed.

Instabilities of thin black rings: closing the gap

Armas

Parisini

2019

We initiate the study of dynamical instabilities of higher-dimensional black holes using the blackfold approach, focusing on asymptotically flat boosted black strings and singlyspinning black rings in D ≥ 5. We derive novel analytic expressions for the growth rate of the Gregory-Laflamme instability for boosted black strings and its onset for arbitrary boost parameter. In the case of black rings, we study their stability properties in the region of parameter space that has so far remained inaccessible to numerical approaches. In particular, we show that very thin (ultraspinning) black rings exhibit a Gregory-Laflamme instability, giving strong evidence that black rings are unstable in the entire range of parameter space. For very thin rings, we show that the growth rate of the instability increases with increasing non-axisymmetric mode m while for thicker rings, there is competition between the different modes. However, up to second order in the blackfold approximation, we do not observe an elastic instability, in particular for large modes m 1, where this approximation has higher accuracy. This suggests that the Gregory-Laflamme instability is the dominant instability for very thin black rings. Additionally, we find a long-lived mode that describes a wiggly time-dependent deformation of a black ring. We comment on disagreements between our results and corresponding ones obtained from a large D analysis of black ring instabilities.Besides having proved to be extremely useful in finding new black hole solutions [14][15][16][17][18] in asymptotically flat space, we demonstrate here that the blackfold approach [7, 19] is a powerful tool for studying hydrodynamic (i.e. Gregory-Laflamme) and elastic instabilities of higher-dimensional black holes in the ultraspinning regime and away from it. 1 In this context, one first finds a stationary solution, modelled as a fluid confined to a surface, corresponding to the black hole solution whose stability one wishes to study. The fundamental fluid variables and the geometric properties of the surface describing the equilibrium configuration of the fluid are subsequently perturbed and the stability properties of black holes are found by studying the propagation of hydrodynamic and elastic modes.Black rings can be classified as thin 0 ≤ ν < 1/2 or as fat 1/2 ≤ ν < 1 where for very thin rings ν = r 0 /R is a measure of the ring thickness. Studying Penrose inequalities, the fat branch of black rings in D = 5 has been shown to be unstable [20][21][22] while for the thin branch in D = 5, the instability of black rings relies on numerical studies [6,12]. However, these numerical studies, due to lack of accuracy, have only established the existence of instabilities for ν ≥ 0.144 [6] and for ν ≥ 0.15 [12]. The region ν < 0.144 is left unknown, with the only suggestive arguments of [7,8] being applicable in the strict case of ν = 0, for which there is barely any distinction between the black ring and the boosted black string. Additionally, the numerical studies of [6,12] have not consid...