Black to white transition of a charged black hole

Polymer models inspired by Loop Quantum Gravity (LQG) have been used to describe non-singular quantum black holes with spherical symmetry, with the classical singularity replaced by a transition from a black hole to a white hole. A recent model, with a single polymerisation parameter, leads to a symmetric transition with same mass for the black and white phases, and to an asymptotically flat exterior metric. The radius of the transition surface is, however, not fixed, increasing with the mass. Following similar procedures, in a previous paper we have fixed that radius by identifying the minimal area on the transition surface with the area gap of LQG. This allowed to find a dependence of the polymerisation parameter on the black hole mass, with the former increasing as the latter decreases. It also permitted to extend the model to Planck scale black holes, with quantum fluctuations remaining small at the horizon. In the present paper we extend this analysis to charged black holes, showing that the Cauchy horizon lies beyond of the transition surface. We also show the existence of limiting states with zero surface gravity, the lightest one with $Q = 0$ and $m = \sqrt{2}/4$, and the heaviest with $Q = m = \sqrt{2}/2$. Using our solutions to approximate quasi-steady horizons, we show that Hawking evaporation leads asymptotically to these extremal states, leaving remnant black holes of Planck size.

Section: Discussionmentioning

confidence: 99%

Remnant loop quantum black holes

Borges,

Baranov,

Sobrinho

et al. 2024

“…See also [101,121] where this equation appears as a definition for the news tensor, in the context of asymptotic infinity.…”

Section: 2i Non-expanding Weakly Isolated and Isolated Horizonsmentioning

confidence: 99%

Carrollian hydrodynamics from symmetries

Freidel¹,

Jai-akson²

2023

In this work, we revisit Carrollian hydrodynamics, a type of non-Lorentzian hydrodynamics which has recently gained increasing attentions due to its underlying connection with dynamics of spacetime near null boundaries, and we aim at exploring symmetries associated with conservation laws of Carrollian ﬂuids. With an elaborate construction of Carroll geometries, we generalize the Randers-Papapetrou metric by incorporating the ﬂuid velocity ﬁeld and the sub-leading components of the metric into our considerations and we argue that these two additional ﬁelds are compulsory phase space variables in the derivation of Carrollian hydrodynamics from symmetries. We then present a new notion of symmetry, called the near-Carrollian diﬀeomorphism, and demonstrate that this symmetry consistently yields a complete set of Carrollian hydrodynamic equations. Furthermore, due to the presence of the new phase space ﬁelds, our results thus generalize those already presented in the previous literatures. Lastly, the Noether charges associated with the near-Carrollian diﬀeomorphism and their time evolutions are also discussed.

“…A non-singular black hole scenario well considered in the literature is the black-to-white transition [8,27,45,47,48], in which two event horizons sit on either side of a bounce. Sine polymer functions realize this scenario already [8].…”

Section: Horizonsmentioning

confidence: 99%

Generic features of a polymer quantum black hole

Münch

Pérez

Speziale

et al. 2023

Non-singular black holes models can be described by modified classical equations motivated by loopquantum gravity. We investigate what happens when the sine function typically used in the modi-fication is replaced by an arbitrary bounded function, a generalization meant to study the effect ofambiguities such as the choice of representation of the holonomy. A number of features can be de-termined without committing to a specific choice of functions. We find generic singularity resolution.The presence and number of horizons is determined by global features of the function regularizing theangular components of the connection, and the presence and number of bounces by global features ofthe function regularizing the time component. The trapping or anti-trapping nature of regions insidehorizons depends on the relative location with respect to eventual bounces. We use these results tocomment on some of the ambiguities of polymer black hole models.