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
Astronomy & Astrophysics
Yunqi Liu, Wei-Liang Qian, Yungui Gong, Bin Wang
Summary: This paper investigates the properties and polarizations of gravitational waves in the scalar-tensor-vector gravity theory, revealing two additional transverse polarization modes due to the interaction between matter and vector field. The stress-energy pseudo-tensor is calculated using the polarization content, and the relaxed field equation for the modified gravity is derived using the Landau-Lifshitz formalism suitable for systems with non-negligible self-gravity.
Article
Physics, Nuclear
Mudassar Sabir, Waqas Ahmed, Yungui Gong, Shan Hu, Tianjun Li, Lina Wu
Summary: We discuss supergravity inflation in braneworld cosmology for the class of potentials V (phi) = alpha phi(n)exp(-beta(m)phi(m)) with m = 1, 2, which can easily accommodate the observational constraints in the high energy regime. The numerical and approximate analytic predictions for the scalar spectral index ns and tensor-to-scalar ratio r are provided, with models preferring smaller n values.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2021)
Article
Physics, Multidisciplinary
Lina Wu, Qing Gao, Yungui Gong, Yiding Jia, Tianjun Li
Summary: In the context of polynomial inflation, we explore the possibility of having a large tensor-to-scalar ratio while still being consistent with quantum gravity corrections and effective field theory. Despite violating the Lyth bound, our numerical computations show that the inflation model can produce a Cosmic Microwave Background (CMB) signal that aligns with data from the Planck satellite. By imposing a specific condition on the field excursion of the inflaton, we predict that the tensor-to-scalar ratio should be smaller than 0.0012 in order for this polynomial inflation scenario to be in agreement with quantum gravity and effective field theory.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2021)
Article
Astronomy & Astrophysics
Fengge Zhang, Yungui Gong, Jiong Lin, Yizhou Lu, Zhu Yi
Summary: The study of non-Gaussianities of primordial curvature perturbations in G-inflation models reveals that even though f(NL) becomes large at certain scales, it remains to be small at peak scales. This suggests that the contributions of non-Gaussianity to scalar induced secondary gravitational waves and primordial black hole abundance are expected to be negligible.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Yingjie Yang, Yungui Gong
Summary: This study used a model-independent method to investigate cosmic curvature and found that the universe may be spatially flat, consistent with the Λ cold dark matter (ΛCDM) model.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Editorial Material
Astronomy & Astrophysics
Yungui Gong
Article
Astronomy & Astrophysics
Jiong Lin, Shengqing Gao, Yungui Gong, Yizhou Lu, Zhongkai Wang, Fengge Zhang
Summary: We address the potential-restriction issue in K/G inflation by introducing nonminimal coupling, where the Higgs field drives inflation in accordance with cosmic microwave background (CMB) observations and enhances curvature perturbations at small scales, thereby explaining the formation of primordial black holes (PBHs) and scalar induced gravitational waves (SIGWs). We further analyze the effect of the noncanonical kinetic coupling function and its observational constraint. Additionally, we provide a gauge invariant expression for the integral kernel of SIGWs, which relates to terms propagating at the speed of light. Lastly, we examine the non-Gaussian effect on the abundance of PBHs and SIGWs, finding that while non-Gaussianity facilitates PBH formation, it has negligible impact on the energy density of SIGWs.
Article
Physics, Particles & Fields
Xuchen Lu, Yungui Gong
Summary: Hubble tension is a significant problem in cosmology, and by recalibrating the luminosity distances using gravitational waves, the issues of zero-point calibration and model dependence in SNe Ia measurements can be resolved.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Chao Zhang, Yungui Gong
Summary: In this study, we investigate extreme mass ratio inspirals and numerically demonstrate that space-based gravitational wave detectors, such as the Laser Interferometer Space Antenna, can detect small charge to mass ratios q of charged particles.
Article
Astronomy & Astrophysics
Ning Dai, Yungui Gong, Tong Jiang, Dicong Liang
Summary: This study investigates the impact of a dark matter minispike around an intermediate massive black hole on the orbital evolution of a binary system. The existence of the minispike leads to deviations from the Keplerian orbit and can potentially be detected in future space-based gravitational wave detectors.
Article
Astronomy & Astrophysics
Hong Guo, Yunqi Liu, Chao Zhang, Yungui Gong, Wei-Liang Qian, Rui-Hong Yue
Summary: We study extreme mass ratio inspirals in modified gravity, modeling a system where a small compact object with scalar charge spirals into a supermassive Kerr black hole. Besides tensorial gravitational waves, radiation is induced by the scalar field. By investigating the dependence of observables on specific spacetime configurations, we find that the presence of additional scalar emission leads to a more significant rate of overall energy loss and has a greater impact on the gravitational radiation produced by a central black hole with higher spin, indicating the possibility of detecting the scalar charge.
Article
Astronomy & Astrophysics
Chunyu Zhang, Yungui Gong, Chao Zhang
Summary: The sky localization of the gravitational wave source can be significantly improved with a network of space-based GW detectors. The improvement is mainly determined by the angle between the detector planes and the time delay, while the effects of arm length and higher harmonics are negligible for source localization.
Article
Astronomy & Astrophysics
Chao Zhang, Yungui Gong, Dicong Liang, Chunyu Zhang
Summary: This study introduces a specific data analysis pipeline for detecting the polarization modes of gravitational waves. Through an example analysis using simulated data, it demonstrates that the method is capable of detecting pure and mixed polarizations without knowing the exact polarization modes.
Article
Astronomy & Astrophysics
Lina Wu, Yungui Gong, Tianjun Li
Summary: The study explores the formation of primordial black hole dark matter and the generation of scalar-induced secondary gravitational waves in generic no-scale supergravity inflationary models. Through the addition of an exponential term to the Kahler potential, ultra-slow-roll inflation is achieved, enhancing the amplitude of the primordial power spectrum at small scales. This leads to a wide mass range of PBHs and accompanying SIGWs with various frequencies.
Article
Astronomy & Astrophysics
Chunyu Zhang, Yungui Gong, Chao Zhang
Summary: Space-based gravitational wave detectors have the advantage of detecting ringdown signals from massive black hole mergers with high signal-to-noise ratios, improving source localization accuracy. Analyzing and studying the properties of binary sources can provide better understanding of gravitational wave signals.
