scholarly journals Late time transitions in the quintessence field and the H0 tension

2019 ◽  
Vol 26 ◽  
pp. 100385 ◽  
Author(s):  
Eleonora Di Valentino ◽  
Ricardo Z. Ferreira ◽  
Luca Visinelli ◽  
Ulf Danielsson
Keyword(s):  
Late Time ◽  
Quintessence Field

scholarly journals Quantum corrections to the accretion onto a Schwarzschild black hole in the background of quintessence

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Kourosh Nozari ◽  
Milad Hajebrahimi ◽  
Sara Saghafi
Keyword(s):  
Black Hole ◽  
Quantum Fluctuations ◽  
Radial Component ◽  
Quantum Corrections ◽  
Back Reaction ◽  
Late Time ◽  
Candidate Model ◽  
Schwarzschild Black Hole ◽  
Singularity Point ◽  
Quintessence Field

AbstractIt is well known that quantum effects may lead to removal of the intrinsic singularity point of back holes. Also, the quintessence scalar field is a candidate model for describing late-time acceleration expansion. Accordingly, Kazakov and Solodukhin considered the existence of back-reaction of the spacetime due to the quantum fluctuations of the background metric to deform a Schwarzschild black hole, which led to a change of the intrinsic singularity of the black hole to a 2-sphere with a radius of the order of the Planck length. Also, Kiselev rewrote the Schwarzschild metric by taking into account the quintessence field in the background. In this study, we consider the quantum-corrected Schwarzschild black hole inspired by Kazakov–Solodukhin’s work, and the Schwarzschild black hole surrounded by quintessence deduced by Kiselev to study the mutual effects of quantum fluctuations and quintessence on the accretion onto the black hole. Consequently, the radial component of the 4-velocity and the proper energy density of the accreting fluid have a finite value on the surface of its central 2-sphere due to the presence of quantum corrections. Also, by comparing the accretion parameters in different kinds of black holes, we infer that the presence of a point-like electric charge in the spacetime is somewhat similar to some quantum fluctuations in the background metric.

scholarly journals A quintessence dynamical dark energy model

2020 ◽  
Author(s):  
Jackie Liu
Keyword(s):  
Dark Energy ◽  
Interesting Property ◽  
Constant Field ◽  
Late Time ◽  
Type Ia ◽  
Monte Carlo Search ◽  
Quintessence Field ◽  
Ia Supernovae ◽  
The Universe ◽  
Dynamical Dark Energy

Abstract We develop a mechanism to generate dynamical dark energy - a quintessence field coupled with gravity. Such model causes the dark energy behaving differently in early and late time universe. In the radiation-dominated-era and matter-dominated-era, the related analytical solutions of the quintessence field have an interesting property - starting as a constant field, then oscillating as the universe expands. By Markov Chain Monte Carlo search of the parameter space with the local measurement (Type Ia supernovae) in the Bayesian framework, the probed range of H0 (within 1σ) overlaps the H0 value inferred from Planck CMB dataset by ΛCDM model.

Scalar-Gauss–Bonnet gravity and cosmic acceleration: Comparison with quintessence dark energy

2017 ◽  
Vol 26 (02) ◽  
pp. 1750008 ◽  
Author(s):  
M. Heydari-Fard ◽  
H. Razmi ◽  
M. Yousefi
Keyword(s):  
Energy Density ◽  
Deceleration Parameter ◽  
Coupling Parameter ◽  
Density Ratio ◽  
Cosmic Acceleration ◽  
Field Energy ◽  
Late Time ◽  
Deceleration Phase ◽  
Quintessence Field ◽  
The Universe

The late-time cosmic acceleration of the universe is explained in the framework of the Einstein-scalar-Gauss–Bonnet (GB) theory by considering different appropriate forms for the GB coupling parameter and the scalar field. The physical quantities such as the potential energy, the GB coupling parameter, the energy density, the pressure and the deceleration parameter are obtained in an exact parametric form of the volume scale factor of the universe. The behavior of the deceleration parameter shows a transition from the deceleration phase to the acceleration phase at the late times in agreement with the observational data. Finally, the GB energy density ratio is compared to the matter energy density and the scalar (the quintessence) field energy density in the early and late times.

scholarly journals Quintessential inflation: A unified scenario of inflation and dark energy

2018 ◽  
Vol 168 ◽  
pp. 04007 ◽  
Author(s):  
Wali Hossain
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Scalar Fields ◽  
Late Time ◽  
Planck Data ◽  
Inflaton Field ◽  
Late Time Acceleration ◽  
Quintessence Field

Quintessential inflation unifies inflation and late time acceleration by a single scalar field. Such a scenario, with canonical and non-canonical scalar fields, has been discussed. The scalar field behaves as an inflaton field during inflation and as a quintessence field during late time. Also the predictions of the models has been compared with the recent Planck data.

scholarly journals Unitarity at the late time boundary of de Sitter

2020 ◽  
Vol 2020 (6) ◽  
Author(s):  
Gizem Şengör ◽  
Constantinos Skordis
Keyword(s):  
Late Time ◽  
De Sitter ◽  
Time Boundary

scholarly journals DARK ENERGY, WITH SIGNATURES

2010 ◽  
Vol 19 (14) ◽  
pp. 2325-2330
Author(s):  
SOURISH DUTTA ◽  
ROBERT J. SCHERRER ◽  
STEPHEN D. H. HSU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Scale ◽  
Fine Tuning ◽  
Time Dependent ◽  
Late Time ◽  
Particle Content ◽  
Energy Field ◽  
Energy Models ◽  
New Energy

We propose a class of simple dark energy models which predict a late-time dark radiation component and a distinctive time-dependent equation of state w(z) for redshift z < 3. The dark energy field can be coupled strongly enough to standard model particles to be detected in colliders, and the model requires only modest additional particle content and little or no fine-tuning other than a new energy scale of order milli-electron volts.

scholarly journals Observations of Hawking radiation: the Page curve and baby universes

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Donald Marolf ◽  
Henry Maxfield
Keyword(s):  
Black Holes ◽  
Quantum Systems ◽  
Late Time ◽  
Asymptotically Flat ◽  
Black Hole Information ◽  
Flat Spacetimes ◽  
The Cost ◽  
Baby Universes ◽  
Time Extrapolation ◽  
Asymptotic Observers

AbstractWe reformulate recent insights into black hole information in a manner emphasizing operationally-defined notions of entropy, Lorentz-signature descriptions, and asymptotically flat spacetimes. With the help of replica wormholes, we find that experiments of asymptotic observers are consistent with black holes as unitary quantum systems, with density of states given by the Bekenstein-Hawking formula. However, this comes at the cost of superselection sectors associated with the state of baby universes. Spacetimes studied by Polchinski and Strominger in 1994 provide a simple illustration of the associated concepts and techniques, and we argue them to be a natural late-time extrapolation of replica wormholes. The work aims to be self-contained and, in particular, to be accessible to readers who have not yet mastered earlier formulations of the ideas above.

scholarly journals Late Time Attractors of Some Varying Chaplygin Gas Cosmological Models

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 769
Author(s):  
Martiros Khurshudyan ◽  
Ratbay Myrzakulov
Keyword(s):  
Dark Energy ◽  
Gravitational Interaction ◽  
Chaplygin Gas ◽  
Cosmological Models ◽  
Late Time ◽  
Time Behavior ◽  
Coincidence Problem ◽  
Energy Models ◽  
Non Linear ◽  
Bayesian Machine Learning

The goal of this paper is to study new cosmological models where the dark energy is a varying Chaplygin gas. This specific dark energy model with non-linear EoS had been often discussed in modern cosmology. Contrary to previous studies, we consider new forms of non-linear non-gravitational interaction between dark matter and assumed dark energy models. We applied the phase space analysis allowing understanding the late time behavior of the models. It allows demonstrating that considered non-gravitational interactions can solve the cosmological coincidence problem. On the other hand, we applied Bayesian Machine Learning technique to learn the constraints on the free parameters. In this way, we gained a better understanding of the models providing a hint which of them can be ruled out. Moreover, the learning based on the simulated expansion rate data shows that the models cannot solve the H0 tension problem.

ICAM-1-independent adhesion of neutrophils to phorbol ester-stimulated human airway epithelial cells

1999 ◽  
Vol 277 (3) ◽  
pp. L465-L471 ◽  
Author(s):  
Alessandro Celi ◽  
Silvana Cianchetti ◽  
Stefano Petruzzelli ◽  
Stefano Carnevali ◽  
Filomena Baliva ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Airway Epithelial Cells ◽  
Bronchial Epithelial Cells ◽  
Neutrophil Adhesion ◽  
Late Time ◽  
Airway Epithelial ◽  
Bronchial Epithelial ◽  
Human Airway ◽  
Stimulation Of ◽  
Human Airway Epithelial Cells

Intercellular adhesion molecule-1 (ICAM-1) is the only inducible adhesion receptor for neutrophils identified in bronchial epithelial cells. We stimulated human airway epithelial cells with various agonists to evaluate whether ICAM-1-independent adhesion mechanisms could be elicited. Phorbol 12-myristate 13-acetate (PMA) stimulation of cells of the alveolar cell line A549 caused a rapid, significant increase in neutrophil adhesion from 11 ± 3 to 49 ± 7% (SE). A significant increase from 17 ± 4 to 39 ± 6% was also observed for neutrophil adhesion to PMA-stimulated human bronchial epithelial cells in primary culture. Although ICAM-1 expression was upregulated by PMA at late time points, it was not affected at 10 min when neutrophil adhesion was already clearly enhanced. Antibodies to ICAM-1 had no effect on neutrophil adhesion. In contrast, antibodies to the leukocyte integrin β-chain CD18 totally inhibited the adhesion of neutrophils to PMA-stimulated epithelial cells. These results demonstrate that PMA stimulation of human airway epithelial cells causes an increase in neutrophil adhesion that is not dependent on ICAM-1 upregulation.

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