While the standard point of view is that the ultimate endpoint of black hole evolution is determined by Hawking evaporation, there is a growing evidence that classical and semi-classical instabilities affect both black holes with inner horizons as well as their ultra-compact counterparts. In this essay we start from this evidence pointing towards extremal black holes as stable endpoints of the gravitational collapse, and develop a general class of spherical and axisymmetric solutions with multiple extremal horizons. Excluding more exotic possibilities, entailing regular cores supporting wormhole throats, we argue that these configuration could be the asymptotic graveyard, the end-point, of dynamical black hole evolution -- albeit the timescale of such evolution are still unclear and possibly long and compatible with current astrophysical observations.
Taming the Aretakis instability: extremal black holes with multi-degenerate horizons
International School for Advanced Studies (SISSA)（高等研究国际学院）；National Institute for Nuclear Physics (INFN), Sezione di Trieste（意大利国家核物理研究所的里雅斯特分部）；Institute for Fundamental Physics of the Universe (IFPU)（宇宙基础物理研究所）
The Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) black hole is an influential solution of the low energy heterotic string theory. As it is well known, it presents a singular extremal limit. We construct a regular extension of the GMGHS extremal black hole in a model with $\mathcal{O}(α')$ corrections in the action, by solving the fully non-linear equations of motion. The de-singularization is supported by the $\mathcal{O}(α')$-terms. The regularised extremal GMGHS BHs are asymptotically flat, possess a regular (non-zero size) horizon of spherical topology, with an $AdS_2\times S^2$ near…
Scalarized Einstein-Euler-Heisenberg black holes at the approach to extremality
Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学天体物理与天文研究所）；School of Science, Jiangsu University of Science and Technology（江苏科技大学理学院）；Center for Quantum Spacetime, Sogang University（西江大学量子时空中心）
A series of corrections to general relativity have recently been applied to find the relationship between entropy and extremality-bound black holes. This relationship has been investigated for many black holes, such as charged AdS, rotating, and massive gravity black holes. We give a minor constant correction to the action and confirm these universal relations for a charged-rotating-AdS black hole. We then examine these calculations for the black hole, surrounded by the quintessence and the cloud of string. In this paper, we evaluate a new universal relation. It means that we find the relation…
We identify a set of higher-derivative extensions of Einstein-Maxwell theory that allow for spherically symmetric charged solutions characterized by a single metric function $f(r)=-g_{tt}=1/g_{rr}$. These theories are a non-minimally coupled version of the recently constructed Generalized Quasitopological gravities and they satisfy a number of properties that we establish. We study magnetically-charged black hole solutions in these new theories and we find that for some of them the equations of motion can be fully integrated, enabling us to obtain analytic solutions. In those cases we show tha…
We semianalytically investigate the scalar self-force experienced in the final stages of extreme mass ratio inspirals of nonspinning scalar particles into supermassive nearly extremal Kerr black holes. We exploit the near-horizon conformal symmetry to find the self-force for general corotating equatorial geodesics. The angular component of the self-force is shown to be universal at leading order in the high spin limit. We verify that the energy and angular momentum losses of the scalar particle match with the asymptotic fluxes of scalar radiation. In particular, we relate the previously descri…
We study Python's lunch geometries in the two-dimensional Jackiw-Teitelboim model coupled to a massless scalar field in the semiclassical limit. We show that all extrema including the minimal quantum extremal surface, bulges and appetizers lie inside the horizon. We obtain fully back-reacted general bulk solutions with a massless scalar field, which can be understood as deformations of black holes. The temperatures of the left/right black holes become in general different from each other. Moreover, in the presence of both state and source deformations at the same time, the asymptotic black hol…
We perform extensive nonlinear numerical simulations of the spherical collapse of (charged) wavepackets onto a charged black hole within Einstein-Maxwell theory and in Einstein-Maxwell-scalar theory featuring nonminimal couplings and a spontaneous scalarization mechanism. We confirm that black holes in full-fledged Einstein-Maxwell theory cannot be overcharged past extremality and no naked singularities form, in agreement with the cosmic censorship conjecture. We show that naked singularities do not form even in Einstein-Maxwell-scalar theory, although it is possible to form scalarized black h…
We set up a new version of black hole information paradox in an eternal Narayan black hole, a generic two-dimensional dilaton gravity theory with non-trivial on-shell bulk action and a product of dimensional reduction from higher-dimensional AdS black brane, joined to Minkowski bath on both sides. We also report both similarities as well as important differences between our model and the famous model of JT gravity coupled with baths. The contradiction of Hawking's result of entanglement entropy with unitarity is resolved by including a new saddle in the Euclidean gravitational path integral. A…
Research Centre for Theoretical Physics and Astrophysics, Institute of Physics, Silesian University in Opava（奥帕瓦西莱斯亚纳大学物理研究所理论与天体物理学研究中心）；Universidad de Tarapacá（塔拉帕卡大学）
Motivated by the prospect of measuring a black hole photon ring, in previous work we explored the interferometric signature produced by a bright, narrow curve in the sky. Interferometric observations of such a curve measure its "projected position function" $\mathbf{r}\cdot\hat{\mathbf{n}}$, where $\mathbf{r}$ parameterizes the curve and $\hat{\mathbf{n}}$ denotes its unit normal vector. In this paper, we show by explicit construction that a curve can be fully reconstructed from its projected position, completing the argument that space interferometry can in principle determine the detailed ph…
