Model-independent cosmological constraints from the CMB

Vonlanthen, Marc; Räsänen, Syksy; Durrer, Ruth

doi:10.1088/1475-7516/2010/08/023

Cited by 73 publications

(112 citation statements)

References 100 publications

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“…d A (τ rec ); (ii) the late ISW effect, affecting only small ; (iii) reionization, suppressing equally all multipoles at 30. It is possible to show [1,2] that all these effects produce just a rescaled amplitude (C → αC ) and position (C → C β ) in the CMB high-multipoles. Then, to remove the dependence on the late-time cosmology we must not only ignore low multipoles and take into account (and marginalize over) the degeneracy between a direct rescaling of the amplitude and position of the CMB multipoles and late time cosmology.…”

Section: Separating Early Cosmology From Late Cosmologymentioning

confidence: 99%

Early cosmology constrained

Verde

Bellini

Pigozzo

et al. 2017

J. Cosmol. Astropart. Phys.

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Abstract. We investigate our knowledge of early universe cosmology by exploring how much additional energy density can be placed in different components beyond those in the ΛCDM model. To do this we use a method to separate early-and late-universe information enclosed in observational data, thus markedly reducing the model-dependency of the conclusions. We find that the 95% credibility regions for extra energy components of the early universe at recombination are: non-accelerating additional fluid density parameter Ω MR < 0.006 and extra radiation parameterised as extra effective neutrino species 2.3 < N eff < 3.2 when imposing flatness. Our constraints thus show that even when analyzing the data in this largely model-independent way, the possibility of hiding extra energy components beyond ΛCDM in the early universe is seriously constrained by current observations. We also find that the standard ruler, the sound horizon at radiation drag, can be well determined in a way that does not depend on late-time Universe assumptions, but depends strongly on early-time physics and in particular on additional components that behave like radiation. We find that the standard ruler length determined in this way is r s = 147.4 ± 0.7 Mpc if the radiation and neutrino components are standard, but the uncertainty increases by an order of magnitude when non-standard dark radiation components are allowed, to r s = 150 ± 5 Mpc.

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Section: Separating Early Cosmology From Late Cosmologymentioning

confidence: 99%

Early cosmology constrained

Verde

Bellini

Pigozzo

et al. 2017

J. Cosmol. Astropart. Phys.

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“…Furthermore, in the FLRW framework, if the curvature Ω k < 0 the space will be a hypersphere and the comoving angular diameter distance will have an upper limit d(z) ≤ 1/ √ −Ω k . The current observation of cosmic microwave background radiation (CMBR) gives the angular diameter distance at z = 1090 is about D A (1090) = 12.8 ± 0.07 Mpc (Vonlanthen et al 2010;Audren et al 2013;Audren 2014). In the meanwhile we also have the direct probe on the current Hubble constant H 0 obtained from the re-analysis of Riess et al (2011) Cepheid data made by Efstathiou (2014) by using a revised geometric maser distance to NGC 4258 from Humphreys et al (2013): H 0 = 72.5 ± 2.5 km/s/Mpc.…”

Section: Determination the Distancesmentioning

confidence: 99%

Revisiting Studies of the Statistical Property of a Strong Gravitational Lens System and Model-Independent Constraint on the Curvature of the Universe

Xia

Wang

et al. 2017

ApJ

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In this paper we use a recently compiled data set, which comprises 118 galactic-scale strong gravitational lensing (SGL) systems to constrain the statistic property of SGL system, as well as the curvature of universe without assuming any fiducial cosmological model. Based on the singular isothermal ellipsoid (SIE) model of SGL system, we obtain that the constrained curvature parameter Ω k is close to zero from the SGL data, which is consistent with the latest result of planck measurement. More interestingly, we find that the parameter f in the SIE model is strongly correlated with the curvature Ω k . Neglecting this correlation in the analysis will significantly overestimate the constraining power of SGL data on the curvature. Furthermore, the obtained constraint on f is different from previous results: f = 1.105 ± 0.030 (68% C.L.), which means that the standard singular isothermal sphere (SIS) model (f = 1) is disfavored by the current SGL data at more than 3σ confidence level. We also divide the whole SGL data into two parts according to the centric stellar velocity dispersion σ c and find that the larger value of σ c the subsample has, the more favored the standard SIS model is. Finally, we extend the SIE model by assuming the power-law density profiles for the total mass density, ρ = ρ 0 (r/r 0 ) −α , and luminosity density, ν = ν 0 (r/r 0 ) −δ , and obtain the constraints on the power-law indexes: α = 1.95 ± 0.04 and δ = 2.40 ± 0.13 at 68% confidence level. When assuming the power-law index α = δ = γ, this scenario is totally disfavored by the current SGL data, χ 2 min,γ − χ 2 min,SIE ≃ 53.

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“…We can circumvent this problem by following the elegant work of Vonlanthen et al (2010), which describes a method for analysing the CMB in a manner that is as independent as possible of late-time cosmology. To this end, the authors begin with identifying the three dominant imprints that the late cosmological model leaves on the observed CMB spectrum.…”

Section: Cosmic Microwave Backgroundmentioning

confidence: 99%

“…But the crucial point is that this insight allowed Vonlanthen et al (2010) to encode unknown secondary effects in carefully chosen nuisance parameters (e.g. the global amplitude of the CMB spectrum).…”

Section: Cosmic Microwave Backgroundmentioning

confidence: 99%

Probing spatial homogeneity with LTB models: a detailed discussion

Redlich

Bolejko

Meyer

et al. 2014

A&A

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Do current observational data confirm the assumptions of the cosmological principle, or is there statistical evidence for deviations from spatial homogeneity on large scales? To address these questions, we developed a flexible framework based on spherically symmetric, but radially inhomogeneous Lemaître-Tolman-Bondi (LTB) models with synchronous Big Bang. We expanded the (local) matter density profile in terms of flexible interpolation schemes and orthonormal polynomials. A Monte Carlo technique in combination with recent observational data was used to systematically vary the shape of these profiles. In the first part of this article, we reconsider giant LTB voids without dark energy to investigate whether extremely fine-tuned mass profiles can reconcile these models with current data. While the local Hubble rate and supernovae can easily be fitted without dark energy, however, model-independent constraints from the Planck 2013 data require an unrealistically low local Hubble rate, which is strongly inconsistent with the observed value; this result agrees well with previous studies. In the second part, we explain why it seems natural to extend our framework by a non-zero cosmological constant, which then allows us to perform general tests of the cosmological principle. Moreover, these extended models facilitate explorating whether fluctuations in the local matter density profile might potentially alleviate the tension between local and global measurements of the Hubble rate, as derived from Cepheid-calibrated type Ia supernovae and CMB experiments, respectively. We show that current data provide no evidence for deviations from spatial homogeneity on large scales. More accurate constraints are required to ultimately confirm the validity of the cosmological principle, however.

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Model-independent cosmological constraints from the CMB

Cited by 73 publications

References 100 publications

Early cosmology constrained

Early cosmology constrained

Revisiting Studies of the Statistical Property of a Strong Gravitational Lens System and Model-Independent Constraint on the Curvature of the Universe

Probing spatial homogeneity with LTB models: a detailed discussion

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