Multiple Transitions in Vacuum Dark Energy and H
               <sub>0</sub> Tension

Moshafi, Hossein; Firouzjahi, Hassan; Talebian, Alireza

doi:10.3847/1538-4357/ac9c58

Cited by 13 publications

(4 citation statements)

References 98 publications

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“…These are shown in Figures 11 and 12. Indeed, multiple transition scenarios have been considered in the literature [39].…”

Section: The Conversion Modelmentioning

confidence: 99%

“…See also [23,24]. Indeed, one of the possible ways to ameliorate these tensions is to consider the possibility that the Universe was originally more anti-de Sitter-(AdS)-like than de Sitter-(dS)like [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. That is, the physics of dark energy (DE) might be more complicated than we initially expected 1 .…”

Section: Introduction: Cosmology With Sign Switching Dark Energymentioning

confidence: 99%

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An Effective Sign Switching Dark Energy: Lotka–Volterra Model of Two Interacting Fluids

Ong

2023

Universe

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One of the recent attempts to address the Hubble and S8 tensions is to consider that the Universe started out not as a de Sitter-like spacetime, but rather anti-de Sitter-like. That is, the Universe underwent an “AdS-to-dS” transition at some point. We study the possibility that there are two dark energy fluids, one of which gave rise to the anti-de Sitter-like early Universe. The interaction is modeled by the Lotka–Volterra equations commonly used in population biology. We consider “competition” models that are further classified as “unfair competition” and “fair competition”. The former involves a quintessence in competition with a phantom, and the second involves two phantom fluids. Surprisingly, even in the latter scenario it is possible for the overall dark energy to cross the phantom divide. The latter model also allows a constant w “AdS-to-dS” transition, thus evading the theorem that such a dark energy must possess a singular equation of state. We also consider a “conversion” model in which a phantom fluid still manages to achieve “AdS-to-dS” transition even if it is being converted into a negative energy density quintessence. In these models, the energy density of the late time effective dark energy is related to the coefficient of the quadratic self-interaction term of the fluids, which is analogous to the resource capacity in population biology.

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“…These are shown in Figures 11 and 12. Indeed, multiple transition scenarios have been considered in the literature [39].…”

Section: The Conversion Modelmentioning

confidence: 99%

Section: Introduction: Cosmology With Sign Switching Dark Energymentioning

confidence: 99%

An Effective Sign Switching Dark Energy: Lotka–Volterra Model of Two Interacting Fluids

Ong

2023

Universe

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“…Early dark energy (EDE) is one of the ideas to solve the Hubble tension [19][20][21][22][23][24]. It is motivated by the string-axion, and behaves like the cosmological constant before the critical epoch a < a c .…”

Section: Introductionmentioning

confidence: 99%

Constraints on the phase transition of early dark energy with the CMB anisotropies

Hayashi

Minoda

Ichiki

2023

J. Cosmol. Astropart. Phys.

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Early dark energy (EDE) models have attracted attention in the context of the recent problem of the Hubble tension. Here we extend these models by taking into account the new density fluctuations generated by the EDE which decays around the recombination phase. We solve the evolution of the density perturbations in dark energy fluid generated at the phase transition of EDE as isocurvature perturbations. Assuming that the isocurvature mode is characterized by a power-law power spectrum and is uncorrelated with the standard adiabatic mode, we calculate the CMB angular power spectra. By comparing them to the Planck data using the Markov-Chain Monte Carlo method, we obtained zero-consistent values of the EDE parameters and H 0 = 67.56+0.65 -0.66 km s-1 Mpc-1 at 68 % CL. This H 0 value is almost the same as the Planck value in the ΛCDM model, H 0 = 67.36 ± 0.54 km s-1 Mpc-1, and there is still a ∼ 3.5σ tension between the CMB and Type Ia supernovae observations. Including CMB lensing, BAO, supernovae and SH0ES data sets, we find H 0 = 68.94+0.47 -0.57 km s-1 Mpc-1 at 68 % CL. The amplitude of the fluctuations induced by the phase transition of the EDE is constrained to be less than 1–2 percent of the amplitude of the adiabatic mode. This is so small that such non-standard fluctuations cannot appear in the CMB angular spectra. In conclusion, the isocurvature fluctuations induced by our simplest EDE phase transition model do not explain the Hubble tension well.

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“…It seems unlikely that this problem is resolved by introducing new particles or interactions [16][17][18][19]. In the context of cosmology, novel proposals have been made recently to remedy the issue [20][21][22], which also address the origin of the HT via a vacuum phase transition [23], Lifshitz vacuum energy [24], early Dark Energy [25][26][27], early Dark Energy plus other components [28,29], interacting Dark Energy [30][31][32], negative Dark Energy density [33], early recombination [34,35], the Dark Matter neutrino interaction [36], self-interacting neutrinos [37][38][39], and other effects [40][41][42][43][44] (see also review paper [45]).…”

Section: Introductionmentioning

confidence: 99%

Hubble tension as a guide for refining the early Universe: Cosmologies with explicit local Lorentz and diffeomorphism violation

Khodadi¹,

Schreck²

2023

Preprint

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This paper is dedicated to assessing modified cosmological settings based on the gravitational Standard-Model Extension (SME). Our analysis rests upon the Hubble tension (HT), which is a discrepancy between the observational determination of the Hubble parameter via data from the Cosmic Microwave Background (CMB) and Type Ia supernovae, respectively. While the latter approach is model-independent, the former highly depends on the model used to describe the physics of the early Universe. Motivated by the HT, we take into account two recently introduced cosmological models as test frameworks of the pre-CMB era. These settings involve local Lorentz and diffeomorphism violation parameterized by nondynamical SME background fields s 00 and s ij , respectively. We aim at explaining the tension in the measured results of the cosmic expansion rate in early and late epochs by resorting to these two modified cosmologies as potential descriptions of the pre-CMB era. As long as the HT does not turn out to be a merely systematic effect, it can serve as a criterion for exploring regions of the parameter space in certain pre-CMB new-physics candidates such as SME cosmologies. By setting extracted limits on SME coefficients into perspective with already existing bounds in the literature, we infer that none of the aforementioned models are suitable pre-CMB candidates for fixing the HT. In this way, new physics arising from the particular realizations of Lorentz and diffeomorphism violation studied in this article does not explain the HT. Our paper exemplifies how to exploit this discrepancy as a novel possibility of refining our description of the early Universe.

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Multiple Transitions in Vacuum Dark Energy and H ₀ Tension

Cited by 13 publications

References 98 publications

An Effective Sign Switching Dark Energy: Lotka–Volterra Model of Two Interacting Fluids

An Effective Sign Switching Dark Energy: Lotka–Volterra Model of Two Interacting Fluids

Constraints on the phase transition of early dark energy with the CMB anisotropies

Hubble tension as a guide for refining the early Universe: Cosmologies with explicit local Lorentz and diffeomorphism violation

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Multiple Transitions in Vacuum Dark Energy and H 0 Tension

Cited by 13 publications

References 98 publications

An Effective Sign Switching Dark Energy: Lotka–Volterra Model of Two Interacting Fluids

An Effective Sign Switching Dark Energy: Lotka–Volterra Model of Two Interacting Fluids

Constraints on the phase transition of early dark energy with the CMB anisotropies

Hubble tension as a guide for refining the early Universe: Cosmologies with explicit local Lorentz and diffeomorphism violation

Contact Info

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Multiple Transitions in Vacuum Dark Energy and H ₀ Tension