Article
Physics, Multidisciplinary
Bilel Hamil, Houcine Aounallah, Prabir Rudra
Summary: In this study, we investigated the effects of higher-order generalized uncertainty principle on the properties of a black hole. Two different GUP models were considered and various aspects of the modified black hole were studied.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Astronomy & Astrophysics
Sina Kazemian, Mateo Pascual, Carlo Rovelli, Francesca Vidotto
Summary: The existence of an area gap as predicted by loop quantum gravity removes a main objection to the scenario where a black hole may leave a remnant with a large amount of stored information at the end of its evaporation. We have modeled the emission from these remnants and derived properties of the diffuse radiation emitted by a population of such objects. By measuring the frequency and energy density of this radiation, it is possible to estimate the mass of the parent black holes and the remnant density, if the age of the population is known.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Physics, Multidisciplinary
Shurui Wu, Bing-Qian Wang, Hao Chen, Zheng-Wen Long
Summary: This study investigates the thermodynamics of the Bardeen black hole with quintessence matter associated with dark energy in the context of the extended generalized uncertainty principle. Using a heuristic method, the corrections to the Hawking temperature, heat capacity, and entropy are obtained. These modifications reveal that the modified uncertainty principles and normalization factor will restrict the lower bound of the horizon radius, thus affecting the Hawking temperature. Additionally, the remnant temperature and mass are independent of the extended uncertainty principle parameter, and the entropy of the Bardeen black hole is not affected by the quintessence matter. Furthermore, the equation of state associated with pressure and volume is examined.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Astronomy & Astrophysics
Yaghoub Heydarzade, Maxim Misyura, Vitalii Vertogradov
Summary: In this study, a novel static spherically-symmetric exact solution of Einstein field equations representing a surrounded hairy black hole is introduced. The effects of the new induced modification terms attributed to the primary hairs and various background fields on geodesic motion are discussed in comparison to the conventional Schwarzschild case. Although these modifications may appear insignificant in most cases, specific conditions are identified where they can be comparable to the Schwarzschild case for certain background fields.
Article
Astronomy & Astrophysics
O. B. Zaslavskii
Summary: This study focuses on the decay of charged and neutral particles in the gravitational field of a black hole. It is found that the growth of energy inside a shell, giving rise to a black-hole bomb, depends on the specific scenario for charged particles, but is impossible for neutral particles. A condition for the existence of a black-hole bomb is identified in the low energy region.
Article
Astronomy & Astrophysics
Marek Szczepanczyk, Sergey Klimenko, Brendan O'Brien, Imre Bartos, V Gayathri, Guenakh Mitselmakher, Giovanni Prodi, Gabriele Vedovato, Claudia Lazzaro, Edoardo Milotti, Francesco Salemi, Marco Drago, Shubhanshu Tiwari
Summary: The detection of GW190521 is the heaviest binary black-hole merger observed to date, providing strong evidence for the existence of intermediate-mass black holes. The significance of this observation was determined by the coherent WAVEBURST (cWB) search algorithm, which identified GW190521 with minimal assumptions of its source model.
Article
Physics, Nuclear
Ningchen Bai, Aoyun He, Jun Tao
Summary: This work investigates the microstructure of charged AdS black holes under minimal length effects. It studies the thermodynamics of black holes and phase transitions based on the generalized uncertainty principle (GUP), and reveals the impact of GUP on the thermodynamic properties and interactions of black holes.
Article
Physics, Multidisciplinary
Homa Shababi, Mohamed Moussa
Summary: This study investigates the effects of generalized uncertainty principle on accretion on Schwarzschild black hole, proposes a modified accretion model, and obtains general critical points locations and conditions. Exact equations for matter density compression and temperature distribution are derived in different scenarios.
INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
Alexandra Chanson, Maria J. Rodriguez
Summary: This article introduces the Blandford-Znajek process for relativistic black hole jets and its application in five-dimensional spacetime. The study obtains solutions to the force-free electrodynamic equations for slowly rotating Myers-Perry black holes, representing plasma magnetospheres. Energy and angular momentum fluxes are calculated for these solutions, allowing for power extraction from higher dimensional black holes. Comparisons are made between the main features of the five-dimensional Blandford-Znajek models and their lower dimensional counterparts.
Article
Astronomy & Astrophysics
Dimitrios Psaltis, Colm Talbot, Ethan Payne, Ilya Mandel
Summary: This paper quantifies the potential upper bounds on black-hole metric deviations based on observations of black-hole shadows and binary black-hole inspirals. The study finds no evidence for deviations from the Kerr metric within the 8 orders of magnitude in mass and 16 orders in curvature spanned by the black holes. Future discoveries of coalescing black-hole binaries with low-mass components may help break the degeneracy between deviation parameters.
Article
Astronomy & Astrophysics
Masato Minamitsuji, Antonio De Felice, Shinji Mukohyama, Michele Oliosi
Summary: We investigate the dynamical properties of static and spherically symmetric systems in the self-accelerating branch of the minimal theory of bigravity (MTBG). In the first part, we study the gravitational collapse of pressureless dust and find special solutions that represent gravitational collapse in MTBG. In the latter part, we study odd-parity perturbations of the Schwarzschild-de Sitter solutions and find that for higher-multipole modes, the system reduces to four physical modes with two dynamical modes and two shadowy modes.
Article
Astronomy & Astrophysics
Lam Hui, Y. . T. Albert Law, Luca Santoni, Guanhao Sun, Giovanni Maria Tomaselli, Enrico Trincherini
Summary: Studies on black hole superradiance often focus on the growth of a cloud in isolation and the spin-down of the black hole. However, this paper considers the additional effect of matter and angular momentum accretion from the surrounding environment. The authors demonstrate that the black hole can evolve by drifting along the superradiance threshold, allowing for analytical or semi-analytical description of its parameter evolution. They also propose the concept of oversuperradiance, where accretion effectively feeds the superradiance cloud through the black hole. Two examples of accretion processes are provided: from a vortex in wave dark matter and from a baryonic disk. The paper also discusses level transition in a similar manner.
Article
Astronomy & Astrophysics
Guillem Domenech, Misao Sasaki
Summary: The end state of Hawking evaporation of a black hole is uncertain. Some quantum gravity theories suggest the existence of Planck sized remnants, such as loop quantum gravity and asymptotic safe gravity. If this is the case, the Universe might be filled with remnants of tiny primordial black holes, formed with mass M<109 M & SIM; 5x105.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Physics, Particles & Fields
Salvatore Capozziello, Rocco D'Agostino, Alessio Lapponi, Orlando Luongo
Summary: We demonstrate the existence of black hole solutions that conform to the thermodynamics of logotropic fluids, which have recently been employed to address cosmological and astrophysical issues, within the framework of the Einstein field equations with a negative cosmological constant. This is accomplished by employing the generalization of logotropic fluids known as the Anton-Schmidt equation of state. We further investigate the construction of the anti-de Sitter metric, satisfying energy conditions, and explore alternative solutions by relaxing the strong energy condition.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Engineering, Mechanical
Xiao Liang, Jiaming Chu, Zhuo Zhou, Congfang Hu, Jinfeng Peng, Baixi Liu, Lin Mo, Jiu Hui Wu, Mei Lin
Summary: This paper investigates turbulent flow in a cavity Acoustic Black Hole (ABH) using numerical and experimental methods, exploring the low frequency sound energy dissipation mechanism under turbulence. The study shows that turbulence in ABH can isolate over 90% of low frequency sound waves, providing a technical solution for the isolation of low frequency sound waves.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Physics, Nuclear
Salwa Alsaleh, Lina Alasfar, Mir Faizal, Ahmed Farag Ali
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2018)
Article
Physics, Multidisciplinary
Abeer Al-Modlej, Salwa Alsaleh, Hassan Alshal, Ahmed Farag Ali
CANADIAN JOURNAL OF PHYSICS
(2019)
Article
Physics, Particles & Fields
Elias C. Vagenas, Ahmed Farag Ali, Hassan Alshal
EUROPEAN PHYSICAL JOURNAL C
(2019)
Article
Physics, Particles & Fields
Elias C. Vagenas, Ahmed Farag Ali, Mohammed Hemeda, Hassan Alshal
EUROPEAN PHYSICAL JOURNAL C
(2019)
Article
Astronomy & Astrophysics
Mohamed Moussa, Homa Shababi, Ahmed Farag Ali
Summary: This paper examines the impact of the generalized uncertainty principle (GUP) on the stochastic gravitational wave (SGW) background signal in the early universe. By modifying the formula for entropy and using pressure parameterizations based on recent lattice calculations, the temporal evolution of temperature and equation of state around the QCD epoch are studied. The results show that the GUP effect leads to an increase in the frequency peak of SGW and weakens the SGW signal generated during the QCD phase transition.
Article
Physics, Particles & Fields
Ahmed Farag Ali, Barun Majumder
Summary: Various approaches to Quantum Gravity suggest the existence of a minimal measurable length, with potential modifications to uncertainty principle, dispersion relation, non-commutative geometry, or Lorentz symmetry. This paper proposes that minimal length can be naturally obtained through spin-orbit interaction, leading to space quantization and indicating a breakdown of space continuum near the scale of tabletop experiments.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Multidisciplinary
Elias C. Vagenas, Ahmed Farag Ali, Mohammed Hemeda, Hassan Alshal
Summary: This paper investigates the massless Reissner-Nordstrom de Sitter metric in the context of minimal length scenarios, proving the confinement of energy density of massless charged particles and their ability to tunnel through the cosmological horizon. The massless particles may interact with Dirac sea, appearing outside the cosmological horizon in dS/CFT holography, potentially providing a fundamental reason for the expansion of the Dirac sea. This could lead to a spacetime Big Crunch.
Article
Physics, Nuclear
Ahmed Farag Ali
Summary: The investigation of Rindler's frame measurements brought about a gravitational interpretation of speed of light, mass, and uncertainty principle from its perspective. This interpretation can be viewed as measurements of a black hole universal clock, leading to the emergence of a timeless state of gravity in a mathematically consistent way – in simple terms, space may be frozen time.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2021)
Article
Astronomy & Astrophysics
Ahmed Farag Ali, Ibrahim Elmashad, Jonas Mureika
Summary: This article presents an argument reinterpreting the generalized uncertainty principle (GUP) and its associated minimal length as an effective variation of Planck constant (h), and suggests that the charge radii and masses of hadrons/nuclei support this effective variation. It also discusses the necessity of varying h and G in explaining the correction to Von Neumann entropy in the Bekenstein-Hawking entropy-area law, and proposes a potential relationship between the effective value of h and the epoch of nucleosynthesis.
Article
Physics, Multidisciplinary
Ahmed Farag Ali, Nader Inan
Summary: In tackling the cosmological constant problem, we postulate that the disagreement between the theoretical and observed values can be attributed to the inherent uncertainties in the spacetime metric. Mach's principle and the concept of a particle as a quantum cloud indicate that the precise location of mass is unknowable, making it difficult to comprehend the quantum-level structure of spacetime. The intriguing connection between quantum and spacetime uncertainties may hold the key to resolving the cosmological constant problem, as the scale of spacetime uncertainty aligns with macroscopic quantum weirdness observed in recent experiments.
Article
Physics, Nuclear
Ahmed Farag Ali, Barun Majumder, Prabir Rudra
Summary: Motivated by the generalized uncertainty principle, the authors establish a discrete model of space that respects both Lorentz symmetry and gauge symmetry. They achieve this by equating the linear GUP correction term and the electromagnetic interaction term in the Dirac equation and derive a wave function that satisfies this equivalence. This discretization may provide an explanation for the crystal and quasicrystal structures observed in nature at various energy scales.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2023)
Article
Physics, Particles & Fields
Kimet Jusufi, Emmanuel Moulay, Jonas Mureika, Ahmed Farag Ali
Summary: We construct an Einstein-Rosen (ER) bridge with a wormhole throat proportional to the zero-point length using a string T-duality corrected pair of regular black holes. This could be a geometric realization of quantum entanglement for particle/antiparticle pairs. The extreme mass configuration of a black hole pair can result in an ER bridge with a horizon area coinciding with the Bekenstein minimal area bound and a wormhole mass proportional to the Planck mass, which may relate to gravitational self-completeness with quantum mechanical mass limits. We also discuss the ER bridge for sub-Planckian mass horizonless wormholes, which exhibits a region of negative energy at the throat, possibly generated by quantum fluctuations or the Casimir effect.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Ahmed Farag Ali, Emmanuel Moulay, Kimet Jusufi, Hassan Alshal
Summary: From a geometric perspective, this article demonstrates that the unitary symmetries U(1) and SU(2) can be fundamentally derived from the Schwarzschild and Reissner-Nordstrom wormhole geometries through spacetime complexification. Quantum tunneling is then explored to enable particle traversal of these wormholes, leading to wormhole thermodynamics.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Multidisciplinary
Omar El-Refy, Syed Masood, Li-Gang Wang, Ahmed Farag Ali
Article
Astronomy & Astrophysics
Elias C. Vagenas, Ahmed Farag Ali, Hassan Alshal
