Dynamical dark energy can amplify the expansion rate of the Universe

Zhang, Hai-Chao

doi:10.1103/physrevd.107.103529

Cited by 6 publications

(6 citation statements)

References 63 publications

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“…Dynamical dark energy is a generalized idea of different values of late-early dark energy (Peebles & Ratra 2003), but with more general dynamics such as Ω Λ ∝ a −3(1+ w( z)) for some variable equation of state w(z) ≠ −1 (Mainini et al 2003;Zhao et al 2017;Di Valentino et al 2023;Zhang 2023). For instance, (Zhao et al 2017) used a large set of observations to constrain the equation of state w(z) of dark energy and found that it oscillates between −0.4 and −2, approximately, for z ä (0, 2).…”

Section: Challenges Of Modern Cosmologymentioning

confidence: 99%

“…For instance, (Zhao et al 2017) used a large set of observations to constrain the equation of state w(z) of dark energy and found that it oscillates between −0.4 and −2, approximately, for z ä (0, 2). Zhang (2023) proposed a model with a small deviation with respect to the standard cosmology during the past and a faster expansion in the future (i.e., at z < 0). On the other hand, Mainini et al (2003) separately modeled slow (classical) or rapid (supergravity) growth, leading to w (z) ∼ ( −0.3, −0.6) and w(z) ∼ ( −0.4, −0.9), respectively, both evolving from z = 10 to z = 0.…”

Section: Challenges Of Modern Cosmologymentioning

confidence: 99%

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What if the Universe Expands Linearly? A Local General Relativity to Solve the “Zero Active Mass” Problem

Monjo

2024

ApJ

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Modern cosmology presents important challenges such as the Hubble Tension, El Gordo’s collision, or the impossible galaxies (z > 10). Slight modifications to the standard model propose new parameters (e.g., the early and dynamical dark energy). On the other hand, alternatives such as the coasting universes (e.g., the hyperconical model and the spatially flat R h = ct universe) are statistically compatible with most of the observational tests, but still present theoretical problems in matching the observed matter contents since they predict a “zero active gravitational mass.” To solve these open issues, we suggest that general relativity might be not valid at cosmic scales, but it would be valid at local scales. This proposal is addressed from two main features of the embedding hyperconical model: (1) the background metric would be independent of the matter content, and (2) the observed cosmic acceleration would be fictitious and because of a distorted stereographic projection of coordinates that produce an apparent radial inhomogeneity from homogeneous manifolds. Finally, to support the discussion, standard observational tests were updated here, showing that the hyperconical model is adequately fitted to Type Ia supernovae, quasars, galaxy clusters, baryon acoustic oscillations, and cosmic chronometer data sets.

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Section: Challenges Of Modern Cosmologymentioning

confidence: 99%

Section: Challenges Of Modern Cosmologymentioning

confidence: 99%

What if the Universe Expands Linearly? A Local General Relativity to Solve the “Zero Active Mass” Problem

Monjo

2024

ApJ

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“…Nevertheless, the nature of this cosmic acceleration is one of the current inquiries in precision cosmology since still we do not fully understand the component with which it is associated, the dark energy. However, due to the well-constrained Λ-Cold Dark Matter (ΛCDM) model, this dark energy could be evidence for a component with a negative Equation-of-State (EoS) constant value [10][11][12] or a dynamical EoS [13][14][15]. Furthermore, dark energy can be associated with components that can be derived from first principles in alternative theories of gravity [16][17][18] and extended theories of gravity [19,20], showing a late cosmic acceleration.…”

Section: Introductionmentioning

confidence: 99%

Constraining dark energy cosmologies with spatial curvature using Supernovae JWST forecasting

Maldonado Alonso,

Escamilla-Rivera,

Sandoval-Orozco

2024

J. Cosmol. Astropart. Phys.

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Recent cosmological tensions, in particular, to infer the local value of the Hubble constant H 0, have developed new independent techniques to constrain cosmological parameters in several cosmologies. Moreover, even when the concordance Cosmological Constant Cold Dark Matter (ΛCDM) model has been well constrained with local observables, its physics has shown deviations from a flat background. Therefore, to explore a possible deviation from a flat ΛCDM model that could explain the H 0 value in tension with other techniques, in this paper we study new cosmological constraints in spatial curvature dark energy models. Additionally, to standard current Supernovae Type Ia (SNIa) catalogs, we extend the empirical distance ladder method through an SNIa sample using the capabilities of the James Webb Space Telescope (JWST) to forecast SNIa up to z ∼ 6, with information on the star formation rates at high redshift. Furthermore, we found that our constraints provide an improvement in the statistics associated with Ω m when combining SNIa Pantheon and SNIa Pantheon+ catalogs with JW forecasting data.

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“…In this line of thought, an interesting path to study both the nature of dark energy and relax (or even solve) cosmological tensions, has been to directly consider the following: (i) A negative equation of state (EoS) constant value [23][24][25]. (ii) A dynamical EoS [26][27][28]. (iii) A dark energy component associated with extra terms obtained from first principles in alternative theories of gravity [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Phantom Scalar Field Cosmologies Constrained by Early Cosmic Measurements

Nájera,

Escamilla-Rivera

2024

Universe

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In this work, we explore new constraints on phantom scalar field cosmologies with a scalar field employing early-time catalogs related to CMB measurements, along with the local standard observables, like Supernovae Type Ia (SNIa), H(z) measurements (Cosmick clocks), and Baryon Acoustic Oscillation (BAO) baselines. In particular, we studied a tracker phantom field with hyperbolic polar coordinates that have been proposed in the literature. The main goal is to obtain precise cosmological constraints for H0 and σ8, in comparison to other constructions that present tension in early cosmological parameters. Our results show that phantom scalar field cosmologies have a reduced statistical tension on H0 that it is less than 3σ using model-independent CMB catalogs as SPT-3G+WMAP9 and ACTPol DR-4+WMAP9 baselines. This suggests that these models, using a different phantom potential, might address the Hubble constant problem and reduce the systematics involved.

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Dynamical dark energy can amplify the expansion rate of the Universe

Cited by 6 publications

References 63 publications

What if the Universe Expands Linearly? A Local General Relativity to Solve the “Zero Active Mass” Problem

What if the Universe Expands Linearly? A Local General Relativity to Solve the “Zero Active Mass” Problem

Constraining dark energy cosmologies with spatial curvature using Supernovae JWST forecasting

Phantom Scalar Field Cosmologies Constrained by Early Cosmic Measurements

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