Article
Astronomy & Astrophysics
P. Tremblin, G. Chabrier, T. Padioleau, S. Daley-Yates
Summary: Inspired by statistical mechanics and fluid mechanics, this study proposes a method to account for small-scale inhomogeneities in self-gravitating astrophysical fluids. By deriving nonideal virial theorem and nonideal Navier-Stokes equations, the study explains the nonideal amplification of gravitational energy and its impact on the dynamics of galaxies and the large-scale Universe. The results demonstrate the importance of considering nonideal effects induced by inhomogeneities.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Ippocratis D. Saltas, Jorgen Christensen-Dalsgaard
Summary: This article discusses general extensions of general relativity that predict a fifth force, which can be tested through precision tests on the solar equilibrium structure. The authors explain how different regions of the Sun can be used to test gravity and demonstrate that the fifth force leaves a signature on the solar sound speed. They also place constraints on the strength of the fifth-force coupling based on observational errors. The findings have significant implications for understanding the nature of gravity and can be applied to theories beyond general relativity.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Vishal Parmar, H. C. Das, M. K. Sharma, S. K. Patra
Summary: This study analyzes the properties of magnetized neutron stars with dark matter. The equation of state is softer with the presence of dark matter and magnetic fields affect different macroscopic properties such as mass, radius, and tidal deformability. The change in neutron star observables is proportional to the amount of dark matter and the strength of the magnetic field.
Article
Astronomy & Astrophysics
Monica N. Castillo-Santos, A. Hernandez-Almada, Miguel A. Garcia-Aspeitia, Juan Magana
Summary: The dynamics of the Universe was analyzed using an exponential function for the dark energy equation of state, known as Gong-Zhang parameterization. The model's free parameters were constrained using various measurements, and it was found that the exponential model is preferred when the data are separated. The cosmological parameters and the age of the Universe were estimated based on the Joint analysis.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Kwing-Lam Leung, Ming-chung Chu, Lap-Ming Lin
Summary: The tidal properties of neutron stars can be measured through gravitational waves, and this has been used to understand the equation of state. This study examines the dimensionless tidal deformability of neutron stars mixed with dark matter. The findings suggest a method to study dark matter parameters by analyzing the tidal properties of compact stars.
Article
Astronomy & Astrophysics
Shin'ichi Nojiri, Sergei D. Odintsov, Diego Saez-Chillon Gomez, German S. Sharov
Summary: This study examines the behavior of dark energy using a general equation of state to address the Hubble parameter tension problem. By analyzing the cosmological evolution and dominance of each term in the equation, interesting consequences such as future singularities are revealed. Fits of free parameters in two general models demonstrate their effectiveness compared to standard models, offering promising insights into understanding the overall cosmological evolution.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Astronomy & Astrophysics
R. R. Cuzinatto, R. P. Gupta, R. F. L. Holanda, J. F. Jesus, S. H. Pereira
Summary: In this paper, the Co-varying Physical Couplings (CPC) framework is introduced, which assumes the gravitational quantities can be treated as space-time functions. By imposing specific constraints, the researchers deduce the functional forms of the couplings as functions of redshift, and demonstrate that this model can describe dark energy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
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
Philip Mocz, Aaron Szasz
Summary: State-of-the-art cosmological simulations on classical computers are limited by time, energy, and memory usage. Quantum computers can perform some calculations exponentially faster than classical computers, using exponentially less energy and memory. However, not all computational tasks exhibit a quantum advantage, and nonlinearities pose a significant challenge. Researchers have proposed a hybrid quantum-classical algorithm framework to overcome this challenge and demonstrate the potential of performing dark matter simulations with quantum computers.
ASTROPHYSICAL JOURNAL
(2021)
Article
Physics, Particles & Fields
C. R. Muniz, V. B. Bezerra, J. M. Toledo
Summary: Investigated Casimir effect between parallel plates around rotating Damour-Solodkhin and Teo wormholes, calculating energy density and comparing results to distinguish characteristics of different types of wormholes and black holes. Discussed Casimir effect in various wormhole spacetimes, as well as influence of gravito-inertial and frame dragging effects on vacuum quantum fluctuations.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Reginald Christian Bernardo, Daniela Grandon, Jackson Levi Said, Victor H. Cardenas
Summary: Through parametric and nonparametric analyses of late-time cosmological data, this study examines dark energy, finding similar evolutions of dark energy density through different methods, indicating that the results are not artifacts of the reconstruction methods applied.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
Deog Ki Hong, Chang Sub Shin, Seokhoon Yun
Summary: The standard cooling scenario in the presence of nucleon superfluidity matches well with observations of neutron stars, providing constraints on new particles. Cooling of young neutron stars is dominated by nucleon pair breaking or electron bremsstrahlung, depending on age and couplings. The study establishes bounds for dark gauge bosons and discusses the possibility of a U(1)(B-L) gauge boson's existence based on rapid cooling of Cas A.
Article
Astronomy & Astrophysics
Ankit Kumar, H. C. Das, S. K. Patra
Summary: Motivated by theoretical studies on efficient dark matter capture by neutron stars, this research explores the indirect effects of captured dark matter on the cooling mechanism of a neutron star. The study shows that varying dark matter momentum greatly modifies neutrino emissivity and investigates specific heat and thermal conductivity of a dark matter admixed star to explore cooling wave propagation within the star.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
German S. Sharov, Vasily E. Myachin
Summary: This study examines cosmological models with variable and modified equations of state for dark energy. It finds that these models have achieved some success in alleviating the tension in the Hubble constant, but further research is still needed.
Article
Astronomy & Astrophysics
Eoin O. Colgain, M. M. Sheikh-Jabbari, Lu Yin
Summary: The study demonstrates that parametric models of dynamical dark energy have a degree of arbitrariness, with errors in wa being sensitive to different redshift functions f(z). Additionally, classic DDE models such as the Chevallier-Polarski-Linder model are less sensitive to DDE, while wiggles uncovered in nonparametric reconstructions require a thorough analysis of correlations.
