Article
Multidisciplinary Sciences
Cosmin Andrei, Anna Ijjas, Paul J. Steinhardt
Summary: In this paper, we investigate how short the remaining period of expansion can be given current observational constraints on dark energy, and discuss how this scenario fits naturally with cyclic cosmologies and recent conjectures about quantum gravity.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Physics, Particles & Fields
Pinki, Pankaj Kumar, Aroonkumar Beesham
Summary: In this paper, the concept of holographic dark energy in the framework of Brans-Dicke theory is reconsidered. The authors investigate the deceleration parameter, Hubble parameter, Brans-Dicke scalar field, and phase transition of the universe. Statefinder diagnostics is applied to compare the model with existing ones.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Asta Heinesen
Summary: This paper discusses redshift drift as a direct probe of violation of the strong energy condition within the theory of general relativity, with a focus on the role of dark energy in the ΛCDM cosmological paradigm. The authors suggest that dark energy and the violation of the strong energy condition may be artifacts of the FLRW model ansatz imposed for interpreting data.
Article
Materials Science, Multidisciplinary
M. Koussour, N. Myrzakulov, S. Myrzakulova, D. Sofuoglu
Summary: This study proposes a novel parametrization approach for the dimensionless Hubble parameter in the context of scalar field dark energy models. The evolution of cosmological parameters is explored using observational data from Cosmic Chronometers, Baryonic Acoustic Oscillations, and the Pantheon+ datasets. The results are compared with the standard ΛCDM model.
RESULTS IN PHYSICS
(2023)
Article
Astronomy & Astrophysics
Rodrigo Calderon, Benjamin L'Huillier, David Polarski, Arman Shafieloo, Alexei A. Starobinsky
Summary: This study aims to reconstruct the expansion history up to large redshifts by using forward-modeling with GP, combining supernovae, baryon acoustic oscillations, and redshift-space distortions data from stage-IV cosmological surveys. The new approach to GP allows for reconstruction of cosmological quantities at high redshifts where data is limited, while also reconstructing the perturbations growth history.
Article
Astronomy & Astrophysics
Deng Wang
Summary: Using the Pantheon+ sample, this study explores new physics on cosmic scales, including interacting dark energy and f(R) gravity models, as well as the evolution of dark energy. While weak constraints are obtained using Pantheon+ alone, strong constraints are achieved when combining with other data sets, indicating a transfer of energy from dark energy to dark matter and a deviation from general relativity. Additionally, a quintessencelike dark energy signal beyond the 2 sigma confidence level is found in a specific redshift range, suggesting a dynamical nature of dark energy.
Article
Physics, Multidisciplinary
Vinod Kumar Bhardwaj, Priyanka Garg, Anirudh Pradhan, Syamala Krishnannair
Summary: In this study, we investigate the power-law entropy corrected holographic dark energy (PLECHDE) model with Hubble horizon cutoff. Using observational data, we constrain the model and calculate relevant cosmological parameters. The results show that the model is consistent with modern observations and matches well with current datasets.
CHINESE JOURNAL OF PHYSICS
(2022)
Article
Astronomy & Astrophysics
Mingzhe Li, Haomin Rao
Summary: The Nieh-Yan modified teleparallel gravity is a model that modifies the general relativity equivalent teleparallel gravity by introducing a coupling between the Nieh-Yan density and an axion-like field. This model predicts parity violations in gravitational waves and avoids the pathologies found in other models. In this paper, the symmetry constraint on the connection is relaxed, leading to a new flat universe solution where scalar and tensor perturbations are coupled.
Article
Physics, Multidisciplinary
Ahmad Sheykhi, Maral Sahebi Hamedan
Summary: The thermodynamics-gravity conjecture suggests a strong connection between the gravitational field equations and the first law of thermodynamics, meaning any changes in entropy expression directly impact the field equations. By considering the modified Barrow entropy associated with the apparent horizon, the Friedmann equations are altered as well. This paper explores the implications of this modification on the holographic dark energy (HDE) model, highlighting changes in energy density and the Friedmann equations. The study also investigates the cosmological consequences of using the Hubble horizon and future event horizon as infrared cutoffs, including interactions between dark matter (DM) and dark energy (DE), and the impact of the Barrow exponent on the cosmological behavior of HDE, such as crossing the phantom line and shifting the universe phase transition time.
Article
Astronomy & Astrophysics
Kyu-Hyun Chae
Summary: The missing gravity in galaxies can be explained by dark matter, modified gravity, or modified inertia. This study compares and tests predictions of cold dark matter halos, modified gravity, and modified inertia using a statistical sample of galaxy rotation curves. The results show that modified gravity correctly predicts the observed statistical relation of accelerations, while cold dark matter halos deviate from the observed relation. The study suggests that modified gravity is the most natural explanation for all aspects of rotation curves.
ASTROPHYSICAL JOURNAL
(2022)
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
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
Physics, Particles & Fields
Armin van de Venn, David Vasak, Johannes Kirsch, Juergen Struckmeier
Summary: The paper investigates the implications of metric compatible covariant canonical gauge theory of gravity on cosmological scales. The resulting equations of motion in a Friedmann-Lemaitre-Robertson-Walker Universe are derived for a totally anti-symmetric torsion tensor. The modifications of the Friedmann equations, equivalent to spatial curvature, are shown in the limit of a vanishing quadratic Riemann-Cartan term and are further investigated in the early and late times of the Universe's history.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Shin'ichi Nojiri, Sergei D. Odintsov, Tanmoy Paul
Summary: In this study, the Bekenstein-Hawking entropy is modified and a new entropy function is developed to derive the usual FLRW equations for matter fluids with different equation of state parameters. The research finds that by using a general entropy based on the Bekenstein-Hawking entropy, the Friedmann equations of the apparent horizon cosmology can be modified, leading to interesting cosmological consequences.
Article
Astronomy & Astrophysics
Priyanka Adhikary, Sudipta Das, Spyros Basilakos, Emmanuel N. Saridakis
Summary: The study discusses the construction of Barrow holographic dark energy in nonflat universe, deriving differential equations for the evolution of dark-energy density parameter and providing analytical expression for the dark energy equation-of-state parameter. The scenario is shown to describe the thermal history of the universe and the sequence of matter and dark energy epochs. Comparisons with flat cases and different spatial geometries reveal interesting behaviors in the evolution of dark-energy equation-of-state parameters under Barrow exponent variations. Incorporating slightly non-flat spatial geometry improves the phenomenology of Barrow holographic dark energy while maintaining smaller values for the new Barrow exponent.