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
Alexander Ganz
Summary: Minimally modified gravity models use auxiliary constraints to maintain a dynamic cosmological background, with results of linear perturbations being insensitive to constraint details, leading to a modified effective gravitational constant or a non-zero dust sound speed.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Chunshan Lin
Summary: This study presents a general covariant local field theory of the holographic dark energy model, showing that the low energy effective theory is the massive gravity theory with a scalar graviton having strong coupling at certain energy scale. The UV-IR correspondence in this model stems from the breakdown of the effective field theory at the energy scale.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
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
Mohammad Ali Gorji, Hayato Motohashi, Shinji Mukohyama
Summary: In the context of scalar-tensor theories, stealth de Sitter solutions face issues of infinite strong coupling or gradient instability, which can be resolved by introducing a controlled detuning mechanism known as scordatura. This mechanism not only resolves the mentioned issues, but also ensures a well-defined quasi-static limit.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Abdolali Banihashemi, Nima Khosravi, Arman Shafieloo
Summary: A new critically emergent dark energy model (CEDE) is proposed, which is consistent with both Planck's CMB data and Riess et al.'s local Hubble constant measurements. The model suggests that dark energy emerges at a transition redshift, providing a possible explanation for the Hubble constant tension.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Alvaro de la Cruz Dombriz, Francisco Jose Maldonado Torralba, David F. Mota
Summary: The stable pseudo-scalar degree of freedom in the quadratic Poincare Gauge theory of gravity is identified as a suitable candidate for dark matter. The study determines the parameter space in the theory that can explain all predicted cold dark matter phenomena and constrains these parameters with astrophysical observations.
Article
Astronomy & Astrophysics
Andreas Lymperis
Summary: By investigating the features of a non-metricity scalar Q function, the cosmological implications of f(Q) gravity are explored, and analytical expressions for the dark energy density, equation-of-state, and deceleration parameters are obtained. The study reveals that even in the absence of a cosmological constant, the universe follows the usual thermal history with matter and dark energy eras, and the dark energy equation-of-state parameter remains in the phantom regime. Additionally, the scenario shows excellent agreement with observational data from Supernovae type Ia. Furthermore, it is demonstrated that f(Q) gravity can effectively mimic the behavior of a cosmological constant.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Mauricio Reyes, Celia Escamilla-Rivera
Summary: This work presents an improvement on Gaussian reconstruction of the Hubble parameter data and explores new constraints in the Horndeski theory of gravity. The research finds that the prior used to calibrate the Pantheon supernovae data significantly affects the reconstructions, with the best fit reconstruction calibrated using the Ho value from The Carnegie-Chicago Hubble Program.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Celia Escamilla-Rivera, Antonio Najera
Summary: The study shows that certain dark energy parametrization models are ruled out and a strong preference against the Chevallier-Polarski-Linder model. A mock GW catalogue suggests that approximately 1000 standard sirens are needed to constrain H-0 within a 1% relative error.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Miguel Aparicio Resco, Antonio L. Maroto
Summary: The study analyzes how to parametrize general modifications of the dark matter perturbations equations in a model-independent way, and shows that a general model with an imperfect and non-conserved dark matter fluid in a modified gravity scenario can be described with five general functions. It focuses on the sub-Hubble regime and finds that observable power spectra are sensitive to only three combinations of the initial five functions, which can help determine whether a modification of gravity or an imperfect/non-conserved dark matter is present. A Fisher forecast analysis for these three parameters is performed, with an example shown for a specific model with shear viscosity.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
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
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
Andreas Finke, Stefano Foffa, Francesco Lacovelli, Michele Maggiore, Michele Mancarella
Summary: This study presents a methodology for correlating 'dark sirens' with galaxy catalogs and explores improvements for gravitational wave detections. The results provide measurements of H-0 and Xi(0), showing interesting constraints for observing dark energy and modifications of gravity at cosmological scales. The study also discusses limits on modified GW propagation under certain conditions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Engineering, Multidisciplinary
Andronikos Paliathanasis, Genly Leon, P. G. L. Leach
Summary: This study applies the Painleve test to the Benney and Benney-Gjevik equations, which are used to describe waves in falling liquids. The research proves that these two nonlinear 1 + 1 evolution equations pass the singularity test for the traveling-wave solutions. Algebraic solutions based on Laurent expansions are presented.
INTERNATIONAL JOURNAL OF NONLINEAR SCIENCES AND NUMERICAL SIMULATION
(2023)
Article
Mathematics, Applied
Andronikos Paliathanasis, Genly Leon
Summary: We investigate exact solutions and the asymptotic dynamics for the Friedmann-Lemaitre-Robertson-Walker universe with nonzero spatial curvature in the fourth-order modified teleparallel gravitational theory known as f(T,B) theory. The field equations can be described in minisuperspace and can reproduce any exact form of the scale factor. Equilibrium points are calculated and their stability is analyzed. Milne and Milne-like solutions are supported, and the existence of a de Sitter universe is shown. Poincare variables are used to investigate the dynamics at infinity in order to complete the analysis.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2023)
Article
Physics, Particles & Fields
Emmanuel N. Saridakis, Weiqiang Yang, Supriya Pan, Fotios K. Anagnostopoulos, Spyros Basilakos
Summary: Soft cosmology extends the standard cosmology by allowing for different equation-of-state parameters for dark matter and dark energy at different scales. Data analysis suggests that soft cosmology is favored by observational constraints.
Article
Astronomy & Astrophysics
Maria Mylova, Jackson Levi Said, Emmanuel N. Saridakis
Summary: This paper constructs the effective field theory (EFT) of the teleparallel equivalent of general relativity (TEGR). The EFT contains more terms compared to the EFT of general relativity (GR) and possesses minor but non-zero differences. However, these differences are suppressed by a heavy mass scale ? and may not be measurable in future experiments and observations.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Shreya Banerjee, Sayantani Bera, David F. Mota
Summary: The Lambda-Cold Dark Matter model is currently the most accurate model for explaining cosmological observations, but there are still issues at galactic scales. Various models of dark matter, such as superfluid dark matter, Bose-Einstein Condensate (BEC) dark matter, and fuzzy dark matter, have been proposed to address these shortcomings. This study investigates these models using the constraint on gravitational wave propagation speed from the detection of the binary neutron star GW170817 by the LIGO-Virgo detector network. The findings suggest that the fuzzy dark matter model is the most feasible scenario to be tested in the near future, especially with detection frequencies < 10-9 Hz.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Theodoros Papanikolaou, Andreas Lymperis, Smaragda Lola, Emmanuel N. Saridakis
Summary: Primordial black holes (PBHs) can be formed through non-canonical inflation, and can provide observational evidence of the early Universe. Constraints on the non-canonical exponents are extracted by requiring significant PBH production. Asteroid-mass PBHs can explain the dark matter, and solar-mass PBHs within the LIGO-VIRGO detection band can be produced. The collapse of enhanced cosmological perturbations that form PBHs can also generate a detectable stochastic gravitational wave (GW) background.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Physics, Multidisciplinary
G. G. L. Nashed, Emmanuel N. Saridakis
Summary: In this study, new classes of anisotropic solutions are extracted within the framework of mimetic gravity. By applying the Tolman-Finch-Skea metric and a specific anisotropy unrelated to it, and smoothly matching the interior solution to the exterior Schwarzschild solution, the authors investigate various properties of these solutions. The results show positive energy density, decreasing pressures towards the center of the star, repulsive anisotropic force, and monotonically increasing equation-of-state parameters. The stability of the solutions is also examined, and it is found that the stars in all cases are stable.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Chemistry, Multidisciplinary
Shreya Banerjee, Sunil K. Gupta, Erode N. Prabhakaran
Summary: The presence of sinusoidal synchronicity between rotational motion along C-alpha-C ' sigma bond and the concomitant pyramidalization of C ' in amides is demonstrated for the first time in solution. It has been found that synchronicity is perturbed when tau-rotation is 'locked' with interactions, resulting in a strain on the amide bond and a decrease in energy barrier for the amide bond cis/trans isomerism by approximately 1.68 kcal/mol.
Article
Physics, Multidisciplinary
Genly Leon, Saikat Chakraborty, Sayantan Ghosh, Raja Solanki, P. K. Sahoo, Esteban Gonzalez
Summary: This paper investigates a non-interacting scalar field cosmology with an arbitrary potential using the f-deviser method. The study presents a unified dynamical system analysis at both the background and perturbation levels, considering arbitrary potentials. A monomial and double exponential potential are used for illustration, as they represent the asymptotic behavior of various scalar field potentials. The linear cosmological perturbations in the matterless case are analyzed, focusing on three scalar perturbations.
FORTSCHRITTE DER PHYSIK-PROGRESS OF PHYSICS
(2023)
Article
Astronomy & Astrophysics
Maria Petronikolou, Emmanuel N. Saridakis
Summary: In this study, we investigate scalar-tensor and bi-scalar-tensor modified theories of gravity that can alleviate the H-0 tension. We show that by choosing particular models with specific features, such as a shift-symmetric friction term or phantom behavior of the effective dark-energy equation-of-state parameter, the tension can be alleviated. These theories provide known mechanisms for alleviating the H0 tension.
Article
Astronomy & Astrophysics
Shreya Banerjee, Maria Petronikolou, Emmanuel N. Saridakis
Summary: We investigate the cosmological applications of gravitational scalar-tensor theories and analyze them in the context of the H0 tension. Two specific models are explored, showing negligible effects at high redshifts but an increasing deviation as time passes. At low redshifts, the Hubble parameter takes on higher values in a controlled manner. This behavior is attributed to the phantom nature of the effective dark-energy equation-of-state parameter, providing a possible solution to the H0 tension. Comparison with cosmic chronometer data demonstrates full agreement within 1σ confidence level.
Article
Physics, Particles & Fields
K. Dialektopoulos, G. Leon, A. Paliathanasis
Summary: The Noether symmetry analysis is used to investigate a multiscalar field cosmological model in teleparallel gravity. Specifically, the study focuses on two scalar fields interacting in scalar-torsion theory. The field equations are described in a minisuperspace framework, and the evolution of physical variables depends on the potential function governing the dynamics of the scalar fields. By requiring the field equations to possess non-trivial Noether point symmetries and utilizing the first theorem of Noether, restrictions are imposed on the functional forms of the potential. Finally, symmetry vectors and corresponding conservation laws are employed to determine exact and analytic solutions in multiscalar-torsion cosmology.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
H. B. Benaoum, Genly Leon, A. Ovgun, H. Quevedo
Summary: This study investigates inflation driven by a nonlinear electromagnetic field based on an NLED lagrangian density. The study formulates an f-NLED cosmological model with a general function f (F) and explores two interesting examples of the function f (F). The study also analyzes the implications of NLED by studying inflationary parameters and compares the results with observational data.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Alfredo D. Millano, Genly Leon, Andronikos Paliathanasis
Summary: In this study, we investigate the dynamics of the field equations in a four-dimensional isotropic and homogeneous spatially flat Friedmann-Lemaitre-Robertson-Walker geometry, using the Einstein-Gauss-Bonnet theory. We consider a matter source and a scalar field coupled to the Gauss-Bonnet scalar. The theory can explain the acceleration phases of the Universe and may be used as a model for studying inflation or as a candidate for dark energy.
Article
Astronomy & Astrophysics
Kimet Jusufi, Genly Leon, Alfredo D. Millano
Summary: This study explains the effect of cold dark matter in the cosmological setup through the coupling between graviton mass and coupling parameter, indicating that dark matter and dark energy are actually surface effects, and provides an equation relating dark matter density, dark energy density, and baryonic matter density.
PHYSICS OF THE DARK UNIVERSE
(2023)
