Challenges for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si238.svg" display="inline" id="d1e11032"><mml:mi mathvariant="normal">Λ</mml:mi></mml:math>CDM: An update

Perivolaropoulos, Leandros; Skara, Foteini

doi:10.1016/j.newar.2022.101659

“…The nature of dark energy can be characterized by its equation of state (EOS) w. The simplest candidate of dark energy is the cosmological constant Λ, whose EOS is w = −1. The cosmological constant dark energy plus the cold dark matter make up the ΛCDM cosmological model, and the wCDM model is obtained if the EOS of dark energy is generalized from −1 to an arbitrary constant w. The simple ΛCDM model fits with observations (eBOSS Collaboration 2021) very well on one hand; however, on the other hand, it is plagued by the Hubble constant (H 0 ) tension (Perivolaropoulos & Skara 2021;Valentino et al 2021). Based on the ΛCDM model, the high-redshift CMB radiation data (Planck Collaboration 2020) give a tight constraint on H 0 (67.4 ± 0.5 km s −1 Mpc −1 ), which deviates from H 0 = 73.2 ± 1.3 km s −1 Mpc −1 given by the low-redshift SN Ia data (Riess et al 2018a(Riess et al , 2018b(Riess et al , 2021 more than 4σ.…”

Section: Introductionmentioning

confidence: 99%

Gamma-Ray Burst Constraints on Cosmological Models from the Improved Amati Correlation

Liu

¹

,

Liang

²

,

Xie

³

et al. 2022

ApJ

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An improved Amati correlation was constructed in ApJ 931 (2022) 50 by us recently. In this paper, we further study constraints on the ΛCDM and wCDM models from the gamma-ray bursts (GRBs) standardized with the standard and improved Amati correlations, respectively. By using the Pantheon Type Ia supernova sample to calibrate the latest A220 GRB data set, the GRB Hubble diagram is obtained model-independently. We find that at the high-redshift region (z > 1.4) the GRB distance modulus from the improved Amati correlation is larger apparently than that from the standard Amati one. The GRB data from the standard Amati correlation only give a lower bound limit on the present matter density parameter Ωm0, while the GRBs from the improved Amati correlation constrain the Ωm0 with the 68% confidence level to be 0.308 − 0.230 + 0.066 and 0.307 − 0.290 + 0.057 in the ΛCDM and wCDM models, respectively, which are very consistent with those given by other current popular observational data including baryon acoustic oscillation, cosmic microwave background (CMB) radiation, and so on. Once the H(z) data are added in our analysis, the constraint on the Hubble constant H 0 can be achieved. We find that two different correlations provide slightly different H 0 results but the marginalized mean values seem to be close to that from the Planck 2018 CMB radiation observations.

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“…Another type of measurement is provided by the Planck collaboration, which uses temperature and polarization anisotropies in the cosmic microwave background (CMB) to obtain H 0 = 67.27±0.6 km s −1 Mpc −1 . The discrepancy between local modelindependent measurements of H 0 and the early Universe CMB values can reach 5.3σ and it is one of the fundamental problems in cosmology ( Schöneberg et al (2019); Di Valentino (2017); Di Valentino et al (2021b,a); Perivolaropoulos & Skara (2022); Lucca (2021); Verde et al (2019); Knox & Millea (2020); Jedamzik et al (2021); Shah et al (2021); Abdalla et al (2022)).…”

Section: Introductionmentioning

confidence: 99%

Constraining the dark energy models using baryon acoustic oscillations: An approach independent of H₀ ⋅ r_d

Staicova

¹

,

Benisty

²

2022

A&A

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The H 0 tension and the accompanying r d tension are a hot topic in current cosmology. In order to remove the degeneracy between the Hubble parameter H 0 and the sound horizon scale r d from the baryon acoustic oscillation (BAO) datasets, we redefined the likelihood by marginalizing over the H 0 • r d parameter and then we performed a full Bayesian analysis for different models of dark energy (DE). We find that our datasets that are uncalibrated by early or late physics cannot constrain the DE models properly without further assumptions. By adding the type Ia supernova (SNIa) dataset, the models are constrained better with smaller errors on the DE parameters. The two BAO datasets we used -one with angular measurements and one with angular and radial ones, with their covariance -show statistical preferences for different models, with the Λ− cold dark matter (ΛCDM) model being the best model for one of them. Adding the Pantheon SNIa dataset with its covariance matrix boosts the statistical preference for the ΛCDM model.

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“…Comparison of theoretical predictions and observations requires LSS data as well, all the more if we take into account that the σ8-tension stems from it. Allowing for some evolution of the vacuum can be the clue to alleviate such a tension [68,70,72], as vacuum dynamics affects nontrivially the cosmological perturbations [142,143]. We consider the perturbed, spatially flat, FLRW metric ds2=−dt2+false(δij+hijfalse) dxidxj, in which hij stands for the metric fluctuations.…”

Section: Some Phenomenological Applications For the Current Universementioning

confidence: 99%

“…In particular, the χH2 part may contain or not the local H0 value measured by Riess et al [77]. The local determination of H0 (which is around 4σ away from the corresponding Planck 2018 value based on the CMB) is the origin of the so-called H0 tension [70–72]. Taking into account that the type I and II RRVM’s have one and two more parameters, respectively, when compared with the normalΛCDM, a fairer model comparison is achieved by computing the numerical differences between the deviance information criterion (DIC) of the normalΛCDM model against the RRVM’s: normalΔDIC=DICnormalΛCDM−DICRRVM.…”

Section: Some Phenomenological Applications For the Current Universementioning

confidence: 99%

The cosmological constant problem and running vacuum in the expanding universe

Peracaula

¹

2022

Phil. Trans. R. Soc. A.

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It is well known that quantum field theory (QFT) induces a huge value of the cosmological constant (CC), Λ , which is outrageously inconsistent with cosmological observations. We review here some aspects of this fundamental theoretical conundrum (the cosmological constant problem, CCP) and strongly argue in favour of the possibility that the cosmic vacuum density ρ vac may be mildly evolving with the expansion rate H . Such a ‘running vacuum model’ (RVM) proposal predicts an effective dynamical dark energy without postulating new ad hoc fields (quintessence and the like). Using the method of adiabatic renormalization within QFT in curved space–time, we find that ρ vac ( H ) acquires a dynamical component O ( H 2 ) caused by the quantum matter effects. There are also O ( H n ) ( n = 4 , 6 , … ) contributions, some of which may trigger inflation in the early universe. Remarkably, the evolution of the adiabatically renormalized ρ vac ( H ) is not affected by dangerous terms proportional to the quartic power of the masses ( ∼ m 4 ) of the quantized matter fields. Traditionally, these terms have been the main source of trouble as they are responsible for the extreme fine-tuning feature of the CCP. In the context under study, however, the late time ρ vac ( H ) around H 0 is given by a dominant term ( ρ vac 0 ) plus the aforementioned mild dynamical component ∝ ν ( H 2 − H 0 2 ) (with | ν | ≪ 1 ), which makes the RVM to mimic quintessence. Finally, on the phenomenological side, we show that the RVM may be instrumental in alleviating some of the most challenging problems (so-called ‘tensions’) afflicting nowadays the observational consistency of the ‘concordance’ Λ CDM model, such as the H 0 and σ 8 tensions. This article is part of the theme issue ‘The future of mathematical cosmology, Volume 2’.

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Challenges for ΛCDM: An update

Cited by 374 publications

References 1,533 publications

Gamma-Ray Burst Constraints on Cosmological Models from the Improved Amati Correlation

Gamma-Ray Burst Constraints on Cosmological Models from the Improved Amati Correlation

Constraining the dark energy models using baryon acoustic oscillations: An approach independent of H₀ ⋅ r_d

The cosmological constant problem and running vacuum in the expanding universe

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Challenges for ΛCDM: An update

Cited by 374 publications

References 1,533 publications

Gamma-Ray Burst Constraints on Cosmological Models from the Improved Amati Correlation

Gamma-Ray Burst Constraints on Cosmological Models from the Improved Amati Correlation

Constraining the dark energy models using baryon acoustic oscillations: An approach independent of H0 ⋅ rd

The cosmological constant problem and running vacuum in the expanding universe

Contact Info

Product

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Constraining the dark energy models using baryon acoustic oscillations: An approach independent of H₀ ⋅ r_d