Determining cosmological parameters with the latest observational data

Xia, Jun-Qing; Li, Hong; Zhao, Gong-Bo; Zhang, Xinmin

doi:10.1103/physrevd.78.083524

Cited by 61 publications

(91 citation statements)

References 88 publications

(79 reference statements)

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“…[67], the authors used the first year WMAP, SDSS and 2dFGRS data to constrain the DE models, and they found that the data evidently favor a strongly time-dependent w DE at present, which is consistent with other results in the literature [68,69,70,71,72,73,74,75,76,77]. As observed in Fig.5, using the latest 5-year WMAP data, combined with SNIa and BAO data, the constraints on the DE parameters of Model B are: w 0 = −1.06 ± 0.14 and w 1 = 0.36 ± 0.62 [34,78,79]. Thus, one deduces that current observational data mildly favor w DE crossing the phantom divide during the evolution of universe.…”

Section: Observational Evidence For Quintom De Scenariosupporting

confidence: 79%

Quintom cosmology: Theoretical implications and observations

et al. 2010

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We review the paradigm of quintom cosmology. This scenario is motivated by the observational indications that the equation of state of dark energy across the cosmological constant boundary is mildly favored, although the data are still far from being conclusive. As a theoretical setup we introduce a no-go theorem existing in quintom cosmology, and based on it we discuss the conditions for the equation of state of dark energy realizing the quintom scenario. The simplest quintom model can be achieved by introducing two scalar fields with one being quintessence and the other phantom. Based on the double-field quintom model we perform a detailed analysis of dark energy perturbations and we discuss their effects on current observations. This type of scenarios usually suffer from a manifest problem due to the existence of a ghost degree of freedom, and thus we review various alternative realizations of the quintom paradigm. The developments in particle physics and string theory provide potential clues indicating that a quintom scenario may be obtained from scalar systems with higher derivative terms, as well as from nonscalar systems. Additionally, we construct a quintom realization in the framework of braneworld cosmology, where the cosmic acceleration and the phantom divide crossing result from the combined effects of the field evolution on the brane and the competition between four and five dimensional gravity. Finally, we study the outsets and fates of a universe in quintom cosmology. In a scenario with null energy condition violation one may obtain a bouncing solution at early times and therefore avoid the Big Bang singularity. Furthermore, if this occurs periodically, we obtain a realization of an oscillating universe. Lastly, we comment on several open issues in quintom cosmology and their connection to future investigations.

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Section: Observational Evidence For Quintom De Scenariosupporting

confidence: 79%

Quintom cosmology: Theoretical implications and observations

et al. 2010

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“…Currently, various observational data favor the simplest concordance cosmological model, which has six free parameters and the pure adiabatic initial condition [1,[3][4][5][6]. Although the concordance model fits the data quite well, it is always worthy to consider alternative candidates.…”

Section: Introductionmentioning

confidence: 99%

Cold dark matter isocurvature perturbations: Cosmological constraints and applications

Liu

Xia

et al. 2011

Phys. Rev. D

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In this paper we present the constraints on cold dark matter (CDM) isocurvature contributions to the cosmological perturbations. By employing Markov Chain Monte Carlo method (MCMC), we perform a global analysis for cosmological parameters using the latest astronomical data, such as 7-year Wilkinson Microwave Anisotropy Probe (WMAP7) observations, matter power spectrum from the Sloan Digital Sky Survey (SDSS) luminous red galaxies (LRG), and "Union2" type Ia Supernovae (SNIa) sample. We find that the correlated mixture of adiabatic and isocurvature modes are mildly better fitting to the current data than the pure adiabatic ones, with the minimal χ 2 given by the likelihood analysis being reduced by 3.5. We also obtain a tight limit on the fraction of the CDM isocurvature contributions, which should be less than 14.6% at 95% confidence level. With the presence of the isocurvature modes, the adiabatic spectral index becomes slightly bigger, n adi s = 0.972 ± 0.014 (1 σ), and the tilt for isocurvature spectrum could be large, namely, the best fit value is n iso s = 3.020. Finally, we discuss the effect on WMAP normalization priors, shift parameter R, acoustic scale lA and z * , from the CDM isocurvaure perturbation. By fitting the mixed initial condition to the combined data, we find the mean values of R, lA and z * can be changed about 2.9σ, 2.8σ and 1.5σ respectively, comparing with those obtained in the pure adiabatic condition.

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“…The above results were obtained from a combination of CMB measurements from the first-year Wilkinson Microwave Anisotropy Probe (WMAP) observations (Bennett et al 2003), the galaxy power spectrum based on the Sloan Digital Sky Survey (SDSS) Data Release 2 (Tegmark et al 2004), the SNe Ia data from Riess et al (2004), and the H 0 prior from the Hubble Space Telescope (HST) Key Project with H 0 =72±8 km s −1 Mpc −1 (Freedman et al 2001). The two models studied in Hannestad (2005) were also constrained in Wang et al (2012) with updated cosmological data, where the (Xia et al 2007(Xia et al , 2008Li & Xia 2012), and revealed the degeneracy between å n m and the EoS ω parameters. In Smith et al (2012), it was found that with non-vanishing curvature density parameter W ¹ 0 k the 95% upper limit on å n m was more than double with respect to the case of a flat universe.…”

Section: Introductionmentioning

confidence: 99%

Constraints on Non-Flat Cosmologies With Massive Neutrinos After Planck 2015

Chen

Ratra

Biesiada

et al. 2016

ApJ

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We investigate two dark energy cosmological models (i.e., the ΛCDM and fCDM models) with massive neutrinos assuming two different neutrino mass hierarchies in both the spatially flat and non-flat scenarios, where in the fCDM model the scalar field possesses an inverse power-law potential, V(f)∝f − α (α>0). Cosmic microwave background data from Planck2015, baryon acoustic oscillation data from 6dFGS, SDSS-MGS, BOSS-LOWZ and BOSS CMASS-DR11, the joint light-curve analysis compilation of SNe Ia apparent magnitude observations, and the Hubble Space Telescope H 0 prior, are jointly employed to constrain the model parameters. We first determine constraints assuming three species of degenerate massive neutrinos. In the spatially flat (non-flat) ΛCDM model, the sum of neutrino masses is bounded as Σm ν <0.165(0.299) eV at 95% confidence level (CL). Correspondingly, in the flat (non-flat) fCDM model, we find Σm ν <0.164(0.301) eV at 95% CL. The inclusion of spatial curvature as a free parameter results in a significant broadening of confidence regions for Σm ν and other parameters. In the scenario where the total neutrino mass is dominated by the heaviest neutrino mass eigenstate, we obtain similar conclusions to those obtained in the degenerate neutrino mass scenario. In addition, the results show that the bounds on Σm ν based on two different neutrino mass hierarchies have insignificant differences in the spatially flat case for both the ΛCDM and fCDM models; however, the corresponding differences are larger in the nonflat case.

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Determining cosmological parameters with the latest observational data

Cited by 61 publications

References 88 publications

Quintom cosmology: Theoretical implications and observations

Quintom cosmology: Theoretical implications and observations

Cold dark matter isocurvature perturbations: Cosmological constraints and applications

Constraints on Non-Flat Cosmologies With Massive Neutrinos After Planck 2015

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