Cosmic viscosity as a remedy for tension between PLANCK and LSS data

Anand, Sampurn; Chaubal, P.; Mazumdar, Arindam; Mohanty, Sanghamitra

doi:10.1088/1475-7516/2017/11/005

Cited by 61 publications

(62 citation statements)

References 94 publications

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“…Let us also mention at this point that there are a few alternative approaches attempting to cure the σ8-tension, e.g. using possible effects of viscosity of the cosmic fluid (Anand et al 2017), or some phenomenological interactions between DM and DE (Barros et al 2018;An, Feng & Wang 2017;Wang et al 2016), or even using a small amount of spatial curvature (Ooba, Ratra & Sugiyama 2017 In fact, dynamical dark energy models may exhibit degeneracies with the cosmic neutrino background since massive neutrinos can suppress the power spectrum (and hence the structure formation) on small scales (see Hu, Eisenstein & Tegmark 1998;Shoji & Komatsu 2010). However, the above mentioned papers show that the effect proves insufficient to relax the σ8-tension, if the allowed neutrino mass hierarchies are to be respected.…”

Section: Analytical Calculation Of ∆ F σ 8 (Z) In the Rvm: Solving Thmentioning

confidence: 99%

Density perturbations for running vacuum: a successful approach to structure formation and to the σ8-tension

Gómez-Valent

Peracaula

2018

Monthly Notices of the Royal Astronomical Society

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Recent studies suggest that dynamical dark energy (DDE) provides a better fit to the rising affluence of modern cosmological observations than the concordance model (ΛCDM) with a rigid cosmological constant, Λ. Such is the case with the running vacuum models (RVMs) and to some extent also with a simple XCDM parametrization. Apart from the cosmic microwave background (CMB) anisotropies, the most crucial datasets potentially carrying the DDE signature are: i) baryonic acoustic oscillations (BAO), and ii) direct large scale structure (LSS) formation data (i.e. the observations on f (z)σ 8 (z) at different redshifts). As it turns out, analyses mainly focusing on CMB and with insufficient BAO+LSS input, or those just making use of gravitational weaklensing data for the description of structure formation, generally fail to capture the DDE signature, whereas the few existing studies using a rich set of CMB+BAO+LSS data (see in particular Solà, Gómez-Valent & de Cruz Pérez 2015and Zhao et al. 2017) do converge to the remarkable conclusion that DDE might well be encoded in the current cosmological observations. Being the issue so pressing, here we explain both analytically and numerically the origin of the possible hints of DDE in the context of RVMs, which arise at a significance level of 3 − 4σ. By performing a detailed study on the matter and vacuum perturbations within the RVMs, and comparing with the XCDM, we show why the running vacuum fully relaxes the existing σ 8 -tension and accounts for the LSS formation data much better than the concordance model.

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Section: Analytical Calculation Of ∆ F σ 8 (Z) In the Rvm: Solving Thmentioning

confidence: 99%

Density perturbations for running vacuum: a successful approach to structure formation and to the σ8-tension

Gómez-Valent

Peracaula

2018

Monthly Notices of the Royal Astronomical Society

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“…In these analyses the base model is normally the ΛCDM cosmology. Although there are many tensions like σ 8 [58][59][60] or H 0 tension [61] among different cosmological measurements under ΛCDM framework still it is undeniable that ΛCDM is the best model available so far to fit the CMB data. The need to accommodate sterile neutrinos, motivated by SBL neutrino oscillation experiments, requires one to introduce large self interaction in the sterile neutrino sector.…”

Section: Discussionmentioning

confidence: 99%

Inflation models in the light of self-interacting sterile neutrinos

2020

Self Cite

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Short baseline neutrino experiments, like LSND and MiniBooNE experiments, pointed towards the existence of eV mass scale sterile neutrinos. To reconcile sterile neutrinos with cosmology self interaction between sterile neutrinos has been studied. We analysed Planck cosmic microwave background (CMB) data with self-interacting sterile neutrino (SIν) and study their impact on inflation models. The fit to the CMB data in SIν model is as good as the fit to ΛCDM model. We find that the spectral index (ns) values shift to 0.9375 ± 0.0058 in SIν model. This has significant impact on the validity of different inflation models. For example the Starobinsky and quartic hilltop model, which were allowed within ΛCDM cosmology, are ruled out. On the other hand some models like natural and Coleman-Weinberg inflation are now favoured. Therefore, the existence of self interacting sterile neutrinos with eV order of mass will play an important role in the selection of correct inflation model. *

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“…The perturbed part of continuity equation for the cold dark matter, T µν ;µ = 0, provides us two basis sets of equations, known as density perturbation equations and velocity perturbation equations [17].…”

Section: )mentioning

confidence: 99%

“…Massive sterile neutrino in the system was reported to reduce the tension in σ 8 -Ω 0 m plane but it fails to do that in H 0 − Ω 0 m [8,15]. Interestingly, in ref [17] it has been shown that viscosities in CDM on large scales solves both σ 8 and H 0 tension simultaneously. We, therefore, use the viscous dark matter description to the study of neutrinos.…”

Section: Introductionmentioning

confidence: 99%