Article
Astronomy & Astrophysics
Sofia Di Gennaro, Yen Chin Ong
Summary: Recent research suggests that black hole remnants of primordial origin are not a suitable candidate for dark matter; however, for models based on non-commutative black holes, the scale of non-commutative effects can reach about 100 times the Planck length.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(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
Astronomy & Astrophysics
Naritaka Oshita, Niayesh Afshordi, Shinji Mukohyama
Summary: This study investigates the ringdown waveform and reflectivity of a Lifshitz scalar field around a fixed Schwarzschild black hole, finding that Lifshitz waves scattered by the black hole exhibit superradiance due to Lorentz breaking terms leading to superluminal propagation. This can allow Lifshitz waves to carry additional positive energy to infinity while leaving negative energy inside the Killing horizon, similar to the Penrose process in Kerr spacetime. The study also observes the emergence of long-lived quasinormal modes and drastic modifications to the greybody factor of a microscopic black hole with Hawking temperature comparable to the Lifshitz energy scale.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Multidisciplinary
Aditya Singh, Aritra Ghosh, Chandrasekhar Bhamidipati
Summary: In this paper, the effect of dark energy on the extended thermodynamic structure and interacting microstructures of black holes in AdS was studied through an analysis of thermodynamic geometry. It was found that dark energy significantly alters the dominant interactions of black hole microstructures, leading to long-ranged repulsive interactions. The Ruppeiner curvature scalar R in the entropy-pressure and temperature-volume planes revealed interesting patterns, especially in charged or rotating AdS black holes with quintessence.
FRONTIERS IN PHYSICS
(2021)
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)
Article
Astronomy & Astrophysics
S. Capozziello, S. Zare, D. F. Mota, H. Hassanabadi
Summary: In this study, the effects of a dark matter spike near the supermassive black hole in M87 (Virgo A galaxy) were investigated using the Bumblebee Gravity theory. The aim was to determine the impact of spontaneous Lorentz symmetry breaking on the horizon, ergo-region, and shadow of the Kerr Bumblebee black hole in the spike region. Dark matter distribution was incorporated into a Lorentz-violating spherically symmetric space-time, and the resulting solution was generalized to a Kerr Bumblebee black hole. The shapes of the shadow were examined based on observational data for the dark matter spike density and radius.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Hooman Davoudiasl, Peter B. Denton, David A. McGady
Summary: The conventional lore excludes fermionic dark matter with mass lighter than a few hundred electronvolts based on the Pauli exclusion principle. A new method is proposed in this paper which involves numerous quasi-degenerate species of fermions without couplings to the standard model to evade this bound. Gravitational interactions impose constraints from measurements at the LHC, cosmic rays, supernovae, and black hole spins and lifetimes, with a particular limit on the number of distinct species of particles being less than or around 10^62.
Article
Astronomy & Astrophysics
Fabio M. Mele, Johannes Muench, Stratos Pateloudis
Summary: In this paper, the authors continue the analysis of the effective model of quantum Schwarzschild black holes. They find that the central singularity is resolved in the quantum-corrected spacetime and quantum effects become relevant at a mass-independent curvature scale. They focus on the thermodynamic properties of the effective polymer black hole and analyze the quantum corrections as functions of black and white hole masses. The study reveals an extremal minimal-sized configuration characterized by vanishing temperature and entropy. For large masses, the classical results are recovered and quantum corrections are negligible.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Daniele Oriti, Xiankai Pang
Summary: The analysis of emergent cosmological dynamics in mean field hydrodynamics of quantum gravity condensates reveals accelerated expansion of the universe at both early and late times. Although it does not support a compelling inflationary scenario in the early universe, it naturally produces a phantom-like dark energy dynamics at late times, which crosses the phantom divide and avoids any Big Rip singularity, approaching a de Sitter universe asymptotically.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Antonio De Felice, Shinji Mukohyama
Summary: This paper introduces a new cosmological framework integrating dark matter into a minimally modified gravity model, maintaining the same number of gravitational degrees of freedom through a series of transformations. The framework includes two time-dependent free functions to achieve desired evolutions of Hubble expansion rate and effective gravitational constant for dark matter.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Yuewei Wen, Eva Nesbit, Dragan Huterer, Scott Watson
Summary: Standard cosmological data analyses can't easily determine the presence of modified gravity. This study presents a quantitative mapping showing how modified gravity models appear within standard analyses, reporting specific biases in standard-parameter spaces. The implications for measurements of mass fluctuations are also discussed.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Suruj Jyoti Das, Devabrat Mahanta, Debasish Borah
Summary: The study investigates the connection between low scale leptogenesis, dark matter, and primordial black holes. It is found that while primordial black holes can affect leptogenesis, they may lead to overproduction of scalar doublet dark matter, with their evaporation usually occurring before dark matter freeze-out. Additionally, primordial black holes can act as a non-thermal source of leptogenesis and dilute thermally generated lepton asymmetry via entropy injection.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
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
Askar Ali, Khalid Saifullah
Summary: In this model, we examine static spherically symmetric black hole surrounded by dark fluid, constructing a new class of magnetized Lovelock black hole solutions and studying their thermodynamics and phase transitions. The mass and thermodynamic quantities of these black holes depend on parameters of the dark fluid and power-Yang-Mills magnetic source, with entropy not following the area law in Gauss-Bonnet and higher order Lovelock black holes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Antonio De Felice, Andreas Doll, Francois Larrouturou, Shinji Mukohyama
Summary: This study investigates spherically symmetric vacuum solutions in the context of the recently proposed type-II minimally modified gravity theory. Despite local differences from the traditional metric, the solutions can be recovered to the standard metric by imposing suitable asymptotic conditions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
