Article
Astronomy & Astrophysics
Yi Ling, Meng-He Wu
Summary: We have constructed a type of regular black holes that have a sub-Planckian Kretschmann scalar curvature. The metric of these regular black holes is characterized by an exponentially suppressing gravity potential, and an asymptotically Minkowski core. Moreover, by choosing different forms of the potential, they can reproduce the metric of the Bardeen/Hayward/Frolov black hole at large scales.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Physics, Multidisciplinary
Marcus A. Khuri, Jordan F. Rainone
Summary: We present the first examples of formally asymptotically flat black hole solutions with horizons of general lens space topology L(p, q). These solutions are five-dimensional static or stationary spacetimes that are regular on and outside the event horizon, and supported by Kaluza-Klein matter fields. Additionally, we obtain new examples of regular gravitational instantons in higher dimensions.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Nuclear
Wei Zeng, Yi Ling, Qing-Quan Jiang
Summary: We investigate the photon sphere and marginally stable circular orbit of regular black holes with sub-Planckian curvature and a Minkowskian core. The stability and location of these orbits are analyzed, and a comparison with other black holes is made. We also discuss the potential of distinguishing between different types of black holes through astronomical observations. Furthermore, we present observational constraints on the deviation parameter for such regular black holes using observed data from the black hole M87*.
Article
Astronomy & Astrophysics
Saulo Carneiro, Pedro C. de Holanda, Alberto Saa
Summary: Extremal rotating black holes can be formed in the Planck energy scattering of Dirac spin parallel neutrinos, with repulsive interaction between their magnetic dipoles induced by vacuum fluctuations. These black holes may have Planck mass and angular momentum, potentially explaining a part of dark matter. Their abundance could be influenced by the energy scale at inflation and chemical potential of primordial neutrinos.
Article
Astronomy & Astrophysics
Pravin K. Dahal, Ioannis Soranidis, Daniel R. Terno
Summary: This article describes the general features of formation and disappearance of regular spherically symmetric black holes in semiclassical gravity. It emphasizes that the escape from a black hole is only possible when the particles are overtaken by the contracting outer apparent horizon. Furthermore, the study also found that the tidal forces experienced by observers at the apparent horizon are finite, but this is not true for non-geodesic trajectories.
Article
Computer Science, Artificial Intelligence
Kaen Kogashi, Yang Wu, Shohei Nobuhara, Ko Nishino
Summary: Human-object interaction (HOI) detection is a crucial vision task that involves detecting individual object instances and reasoning their relations. The challenge lies in detecting HOI instances with missing objects, which are prevalent in commonly-used public datasets. This paper introduces a novel method that incorporates global scene information for effective and superior HOI detection performance.
IMAGE AND VISION COMPUTING
(2021)
Article
Astronomy & Astrophysics
Astrid Eichhorn, Aaron Held, Philipp-Vincent Johannsen
Summary: By observing the shadow images of black holes, we can investigate the effects of quantum gravity and other mechanisms on singularity resolution beyond traditional quantum gravity theories. Even the current accuracy of the Event Horizon Telescope (EHT) is sufficient to place meaningful constraints on the scale of new physics, when combined with an independent measurement of the black hole mass for M87*. Higher accuracy from the next-generation EHT is required for other spacetimes. Additionally, we study the concept of localized emission regions inspired by hotspots in accretion flows, as well as the photon-ring structure of horizonless objects where photon rings annihilate each other in the absence of photon spheres.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Physics, Particles & Fields
Pei-Ming Ho, Hikaru Kawai, Yuki Yokokura
Summary: In the context of a gravitational collapse, the transition amplitudes for the creation of particles due to higher-derivative interactions were computed, revealing that these amplitudes grow exponentially with time and peak when the collapsing matter is approximately a Planck length away from the horizon, leading to the breakdown of the effective theory at the scrambling time. This invalidates its prediction of Hawking radiation, allowing Planckian physics to influence the fate of black hole evaporation.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Astronomy & Astrophysics
Alejandro Perez, Daniel Sudarsky
Summary: Research suggests that noisy energy momentum diffusion due to space-time discreteness at the Planck scale can lead to the generation of a cosmological constant during the cosmic evolution. Although this diffusion mechanism has minimal effect on standard astrophysical matter, it may still be important for black holes. Taking such effects into account could potentially solve the 'H-0 tension' and the low rotational spin of black holes observed via gravitational wave astronomy.
GENERAL RELATIVITY AND GRAVITATION
(2021)
Article
Astronomy & Astrophysics
I. J. Araya, N. D. Padilla, M. E. Rubio, J. Sureda, J. Magana, L. Osorio
Summary: We investigate the presence of electric charge in primordial black holes (PBHs) up to the present time. It is found that PBHs can possess a non-zero net charge at their formation, either due to Poisson fluctuations during horizon crossing or high-energy particle collisions. Despite rapid discharge processes such as particle accretion or quantum particle emission, PBHs with maximum rotation can generate magnetic fields that could shield them from discharge. Additionally, the plasma within virialized dark matter haloes can endow PBHs with a net negative charge, considering that electrons are the lightest and fastest charge carriers. We report charge-to-mass ratios ranging from 10-31 C/kg to 10-15 C/kg for PBHs within the mass windows allowing them to constitute the entirety of the dark matter in the Universe.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Physics, Nuclear
Meirong Tang, Zhaoyi Xu, Jiancheng Wang
Summary: This study reveals a significant enhancement effect of dark matter on the orbital eccentricity of a black hole in an intermediate-mass-ratio-inspiral (IMRI) system, which can be detected by future space-based gravitational wave detectors. The study also shows that different densities of dark matter and masses of center black holes can influence the eccentricity of the system, providing new insights for detecting black hole mass. Furthermore, the research suggests that it is possible to differentiate dark matter models by measuring the eccentricity at a certain scale.
Article
Astronomy & Astrophysics
Valerio De Luca, Justin Khoury
Summary: Superfluid dark matter, a novel theory of self-interacting light particles that form a superfluid in galaxies, matches the standard ACDM model on cosmological scales and offers unique phenomena on galactic scales. The density profile of superfluid dark matter around supermassive black holes in galaxies is computed, showing distinct power-law behaviors that can distinguish it from collisionless dark matter.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Bartlomiej Kiczek, Marek Rogatko
Summary: This study conducted numerical analysis of a dark matter axionlike cloud near a rotating black hole, studying a model where an axionlike scalar field is coupled to the Maxwell field. It was found that condensation of the axion dark matter cloud is preferable for a very small mass of axion.
Article
Astronomy & Astrophysics
Bob Holdom, Robert B. Mann, Chen Zhang
Summary: The response of a static Unruh-DeWitt detector outside an exotic compact object (ECO) in 3 + 1 dimensions has been studied. It was found that the response rate is notably distinct from the black hole case, even when the wave is lost completely to damping. Resonance structures in the response rate were observed for partial or no damping, depending on the compactness of the ECO and the detector location.
Article
Astronomy & Astrophysics
Zhaoyi Xu, Jiancheng Wang, Meirong Tang
Summary: Research shows that dark matter spikes have a significantly higher impact on black holes compared to dark matter halos, potentially greatly increasing the chances of detecting dark matter signals near black holes, and thus providing the possibility to test dark matter models through gravitational wave and EHT observations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
