Article
Astronomy & Astrophysics
Daniela Perez, Gustavo E. Romero
Summary: This study analyzes whether a black hole can survive in a universe that undergoes cosmological bounce. The findings suggest that in a specific class of bouncing models, black holes can exist at different cosmological epochs, potentially playing a role in the subsequent cosmic expansion.
Article
Physics, Particles & Fields
Archil Kobakhidze, Zachary S. C. Picker
Summary: By analysing the nature of the horizon, we demonstrate the validity of the Thakurta metric in describing cosmological black holes, contrary to some claims in the literature.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Multidisciplinary
J. P. Morais Graca, Eduardo Folco Capossoli, Henrique Boschi-Filho
Summary: In this work, we studied the Joule-Thomson expansion for uncharged black holes in a noncommutative scenario characterized by a parameter theta, finding that the uncharged noncommutative black hole behaves as a charged commutative one under certain conditions.
Article
Astronomy & Astrophysics
A. Crespo-Hernandez, E. A. Mena-Barboza, M. Sabido
Summary: This paper proposes a generalization to the Schwarzschild metric and introduces noncommutative SUSY black holes. The noncommutative deformation to the minisuperspace variables is introduced, and the noncommutative supersymmetric Wheeler-DeWitt equation for the Schwarzschild black hole is derived. The metric is calculated and it is found that the singularities are not removed.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2022)
Article
Astronomy & Astrophysics
Javlon Rayimbaev, Ashfaque Hussain Bokhari, Bobomurat Ahmedov
Summary: The study investigates the dynamics of test particles in the spacetime of noncommutative inspired black holes, analyzing properties such as innermost stable circular orbits and Keplerian orbits frequencies. It is found that the effects of NC parameter on quasiperiodic oscillations frequencies are smaller than the measurement error. The method for testing gravity using twin-peak QPOs frequencies can be applied to other theories of gravity to restrict central BH parameters.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Sam Young
Summary: In this study, we reassess the impact of local-type non-Gaussianity on the abundance of primordial black holes (PBHs) and find that the effect is much less significant than previously believed. The non-Gaussianity parameters need to be significantly larger to have a similar effect as before, which weakens the constraints on PBH abundance and the primordial power spectrum dependence on non-Gaussianity parameters. Furthermore, we question the existing calculations of PBH abundance due to the correlation between curvature perturbation and compaction.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Raphal van Laak, Sam Young
Summary: Primordial black holes are black holes that may have formed in high density regions in the early universe. The fluctuations in their formation rate can be used to constrain the amplitude of non-Gaussianity, especially if primordial black holes make up a significant fraction of dark matter. By extending the calculation to include peaks theory and considering the non-linearities between compaction C and curvature perturbation C, we find that the constraints on quadratic models of non-Gaussianity are largely unchanged, while the constraints on cubic models significantly worsen. If all of the dark matter is composed of primordial black holes, the parameters of non-Gaussianity are -2.9 & BULL; 10-4 < f < 3.8 & BULL; 10-4 and -1.5 & BULL; 10-3 < g < 1.9 & BULL; 10-3 for quadratic and cubic models respectively.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Yi-Fu Cai, Xiao-Han Ma, Misao Sasaki, Dong-Gang Wang, Zihan Zhoua
Summary: This paper investigates the relationship between deviations from Gaussian statistics in primordial perturbations and non-perturbative effects. It presents specific examples where the tail of the distribution becomes highly non-Gaussian despite remaining almost Gaussian in the perturbative regime. The study reveals the rich phenomenology of non-Gaussian tails, which has been overlooked in conventional analyses.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Yves Brihaye, Betti Hartmann
Summary: In this paper, the authors re-examine charged Q-clouds around spherically symmetric, static black holes and find two different branches of charged scalar clouds. Furthermore, they discover that the new solutions have a 'hard wall' at the maximal possible gauge coupling, separating the interior from the exterior. Taking back-reaction onto the space-time into account, they find that at maximal possible back-reaction, black hole solutions corresponding to these two branches exhibit specific behaviors.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
David Matejov, Jiri Podolsky
Summary: In this paper, we generalize our previous work on the geometry of axially symmetric extremal isolated horizons in asymptotically flat spacetime to include EIHs in asymptotically (anti-)de Sitter spacetime. The resulting metric depends on several parameters and is consistent with results obtained in the context of near-horizon geometries. We also study the extremal horizons of all black holes within the Plebanski-Demianski exact (electro)vacuum spacetimes of the algebraic type D, and identify the corresponding extremal horizons for the Kerr-Newman-NUT-(A)dS metric, including their position and geometry.
Article
Astronomy & Astrophysics
Jose M. M. Senovilla
Summary: It has been shown that spacetimes with a positive cosmological constant Lambda > 0 containing spatially stable marginally trapped surfaces (MTSs) approaching the upper bound area acquire universal properties. These spacetimes possess generalized 'holographic screens' composed of MTSs with spherical topology, which include a dynamical horizon portion and a timelike membrane portion. These results have significant implications for BH mergers and compact objects accreting mass from their surroundings.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Mathematics, Applied
Carlos Castro Perelman
Summary: This study demonstrates the consistency between the radial spectrum of a fuzzy sphere in a noncommutative phase space characterized by the Yang algebra and the Regge spectrum. It also reveals the quantization properties of the mass-angular momentum relation and the holographic nature, as well as the relationship between the Yang algebra and the Lorentz algebra in the noncommutative phase space.
JOURNAL OF GEOMETRY AND PHYSICS
(2022)
Article
Physics, Multidisciplinary
Daniel Frolovsky, Sergei V. V. Ketov, Sultan Saburov
Summary: In this study, new (generalized) E-type alpha-attractor models are proposed and studied in order to explain the formation of primordial black holes (PBHs). The models involve three different phases of inflation, and numerical calculations are used to obtain the power spectrum of scalar perturbations and PBH masses. It is found that for certain parameter values, asteroid-size PBHs with masses ranging from 10^17 to 10^19 grams can be formed, which may serve as a candidate for dark matter in the present Universe. Furthermore, it is suggested that the gravitational waves produced by the formation of PBHs can potentially be detected by future space-based gravitational interferometers.
FRONTIERS IN PHYSICS
(2022)
Article
Astronomy & Astrophysics
Giacomo Ferrante, Gabriele Franciolini, Antonio Junior Iovino, Alfredo Urbano
Summary: We revise the production of primordial black holes (PBHs) in the axion-curvaton model by considering recent developments in the computation of their abundance accounting for nongaussianities (NGs) in the curvature perturbation. We find that the intrinsic NGs generated in such scenarios have a significant impact on the phenomenology associated with PBHs, particularly on the relationship between their abundance and the second order gravitational wave signal. Additionally, we demonstrate that this model can potentially explain the entire dark matter content in the asteroid mass range and the signal reported in the nano-Hz frequency range by the NANOGrav and IPTA collaborations. Along the way, we provide a new explicit computation of the power spectrum of curvature perturbations that goes beyond the sudden decay approximation.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Ankur, Sanjib Dey
Summary: We have studied charged BTZ black holes in noncommutative spaces using two independent approaches. The first approach revealed the existence of non-static and non-stationary black holes, while the second approach provided stability and physical viability by introducing proper restrictions on the noncommutative parameter. The thermodynamics of the black holes from both approaches were analyzed using a contemporary tunneling formalism.
Article
Astronomy & Astrophysics
Jerry Wu, Robert B. Mann
Summary: We present the first examples of phase transitions in asymptotically flat black hole solutions. We find stable temperature regions for otherwise unstable neutral black holes, indicating the existence of multiple stable phases that can coexist at multi-critical points. For charged black holes, multiple first order phase transitions can occur on the stable Gibbs free energy branch, similar to anti-de Sitter (AdS) black holes. The changes in Gibbs free energy are investigated and compared to pressure changes for AdS black hole systems.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Jerry Wu, Robert B. Mann
Summary: We find that there are multi-critical points, where more than three phases coalesce, in multiply rotating Kerr-anti de Sitter black holes in d-dimensions. Specifically, we present a quadruple point for a triply rotating black hole in d = 8 and a quintuple point for a quadruply rotating black hole in d = 10. The maximal number of distinct phases n is one larger than the maximal number of independent rotations, and we outline a method for obtaining the associated n-tuple point. There are also situations where more than three phases merge at sub-maximal multi-critical points. Our results indicate that multi-critical points in black hole thermodynamics are more common than previously believed, as long as there are a sufficient number of thermodynamic variables.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Physics, Multidisciplinary
Jack Davis, Robie A. Hennigar, Robert B. Mann, Shohini Ghose
Summary: The Majorana stellar representation is used to characterize spin states with maximally negative Wigner quasiprobability distributions. These states exhibit partial symmetry within their star configurations and do not follow an obvious geometric pattern with increasing dimension. They are also different from states that maximize other measures of nonclassicality. Random states have a relatively high amount of negativity, but extremal states and those with similar negativity are statistically rare in Hilbert space. Spin coherent states of arbitrary dimension have non-zero Wigner negativity, suggesting that all pure spin states have non-zero Wigner negativity. These results can be applied to permutation invariant qubit ensembles.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2023)
Article
Astronomy & Astrophysics
H. Khodabakhshi, H. Lu, R. B. Mann
Summary: The gravitational Lagrangian can be decomposed into a bulk term and a total derivative term. In certain theories of gravity like Einstein or Lovelock gravities, there are holographic relations between the bulk and the total derivative term, where the latter is determined by the former. However, at the D -> 2 and D -> 4 limits, the bulk terms of Einstein or Gauss-Bonnet theories become total derivatives themselves. Performing the Kaluza-Klein reduction on Einstein and Gauss-Bonnet gravities leads to two-dimensional or four-dimensional scalar-tensor theories respectively. We derived holographic relations for the D = 2 and D = 4 cases, which have the same form as the holographic relations in pure gravity in the foliation independent formalism.
Article
Physics, Particles & Fields
Gareth Arturo Marks, Robert B. Mann, Damian Sheppard
Summary: We study slowly rotating black hole solutions in the six independent theories of Quartic Generalized Quasi-topological Gravity in four dimensions. Unlike in the static case, for rotating black holes we obtain distinct results for five out of the six theories. We construct approximate and numerical solutions to these equations, and study how physical properties of the solutions are modified, working to leading order in the coupling constant.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
Everett Patterson, Robert B. Mann
Summary: Relativistic quantum metrology is the study of optimal measurement procedures in systems with quantum and relativistic components. In this study, we analyze thermal parameters in different spacetimes using Unruh-DeWitt detectors coupled to a massless scalar field. We consider both (2+1)-dimensional anti-de Sitter and BTZ black hole spacetimes and compute the Fisher information to identify characteristics and maximize precision.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
Jiayue Yang, Robert B. Mann
Summary: Treating the horizon radius as an order parameter, the study investigates the dynamic behavior of black hole phase transitions using the free energy landscape model. The first investigation of the recently discovered multicriticality in black holes is carried out. By numerically solving the Smoluchowski equation, thermodynamic phase transitions and oscillatory phenomena are observed at black hole quadruple points in D = 4 Einstein gravity coupled to non-linear electrodynamics. The probability distribution of the final stationary state is found to be closely related to the structure of its off-shell Gibbs free energy.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Quantum Science & Technology
Ireneo James Membrere, Kensuke Gallock-Yoshimura, Laura J. Henderson, Robert B. Mann
Summary: The first investigation on tripartite entanglement harvesting near a black hole is conducted. In the static Banados-Teitelboim-Zanelli (BTZ) black hole spacetime, the authors find that it is possible to harvest tripartite entanglement in regions where harvesting of bipartite entanglement is impossible due to intense Hawking radiation. In these situations, the harvested entanglement is of the Greenberger-Horne-Zeilinger (GHZ) type.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Astronomy & Astrophysics
Moaathe Belhaj Ahmed, David Kubiznak, Robert B. Mann
Summary: An isolated critical point refers to a unique thermodynamic critical point in higher dimensions of Kth-order Lovelock gravity with hyperbolic black holes, achieved by fine-tuning Lovelock coupling constants. It represents the merging of two swallowtails and exhibits unconventional critical exponents. By applying a recent proposal for topological charge assignment to thermodynamic critical points, the isolated critical point is suggested to indicate the onset of a topological phase transition of a vortex-antivortex pair.
Article
Astronomy & Astrophysics
Dyuman Bhattacharya, Kensuke Gallock-Yoshimura, Laura J. Henderson, Robert B. Mann
Summary: We investigate the changes in initial entanglement of two initially entangled Unruh-DeWitt particle detectors after interacting with a quantum scalar field. Similar to separable detectors, entangled detectors can gain more entanglement from the field as long as they are weakly correlated at the beginning. Only degradation occurs for initially sufficiently entangled detectors. We then analyze the case of a gravitational shock wave spacetime and demonstrate that the shock wave can enhance the initial entanglement, even for greater detector separations than in Minkowski spacetime.
Article
Astronomy & Astrophysics
Jerry Wu, Robert B. Mann
Summary: We demonstrate that black holes in Lovelock gravity with order N≥4 can exhibit multicritical phase behavior. We provide explicit examples of quadruple points in d=10 fourth-order Lovelock gravity and quintuple points in d=14 sixth-order Lovelock gravity. We also show that multicriticality can be realized for uncharged, nonrotating black holes by introducing a new type of multicritical point between black holes and thermal radiation. Additionally, we discuss the methodology used and compare it to other black hole multicritical points in terms of the Gibbs phase rule.
Article
Astronomy & Astrophysics
Ahmed Shalabi, Laura J. Henderson, Robert B. Mann
Summary: The potential breakdown of the metric at high energy scales could suggest a fundamental minimal length scale. One approach to this minimum length scale is to construct a quantum field theory with a bandlimit on the field. We investigate the effects of implementing such a bandlimit on a field in a curved and compact spacetime, and how to detect it.
Article
Astronomy & Astrophysics
Manar Naeem, Kensuke Gallock-Yoshimura, Robert B. Mann
Summary: We studied the mutual information harvesting protocol for two uniformly accelerated particle detectors. Our numerical calculations demonstrate that, although a single detector behaves as if it is in a thermal bath, the quantum mutual information between two accelerating detectors differs from that of two inertial detectors in a thermal bath. This discrepancy arises because the Wightman function along the trajectory of a single uniformly accelerating detector is the same as that of a detector in a thermal bath, but a pair of detectors in the respective cases have different Wightman functions.
Article
Astronomy & Astrophysics
Brayden R. Hull, Robert B. Mann
Summary: We demonstrate the existence of asymptotically de Sitter black holes of negative mass in Lovelock gravity. These black holes have horizon geometries with nonconstant curvature and are known as exotic black holes. We specifically study the case of Gauss-Bonnet gravity. We discuss the impact of transverse space geometry on the existence of black holes for both positive and negative mass solutions and provide closed form bounds for geometric parameters.
Article
Astronomy & Astrophysics
Amjad Ashoorioon, Mohammad Bagher Jahani Poshteh, Robert B. Mann
Summary: Accelerating black holes, connected to cosmic strings, could evolve into supermassive black holes. However, the acceleration should be small in order for them to participate in structure formation and reside at the center of galaxies. Although this slow acceleration does not significantly change the shadow or image position in gravitational lensing, it does significantly affect the time delay associated with these images.