Date Published:

July 1, 2017

Abstract:

We develop a new computationally efficient methodology calleddouble-probe analysis with the aim of minimizing informative priors(those coming from extra probes) in the estimation of cosmologicalparameters. Using our new methodology, we extract the dark energymodel-independent cosmological constraints from the joint data sets ofthe Baryon Oscillation Spectroscopic Survey (BOSS) galaxy sample andPlanck cosmic microwave background (CMB) measurements. We measure themean values and covariance matrix of {R, l_a,Ω_bh², n_s, log(A_s),Ω_k, H(z), D_A(z),f(z)σ₈(z)}, which give an efficient summary of thePlanck data and two-point statistics from the BOSS galaxy sample. TheCMB shift parameters are R=√{Ω _m H_0^2} r(z_*) andl_a = πr(z_*)/r_s(z_*), wherez_* is the redshift at the last scattering surface, andr(z_*) and r_s(z_*) denote our comovingdistance to the z_* and sound horizon at z_*,respectively; Ω_b is the baryon fraction at z = 0. Thisapproximate methodology guarantees that we will not need to putinformative priors on the cosmological parameters that galaxy clusteringis unable to constrain, I.e. Ω_bh² andn_s. The main advantage is that the computational timerequired for extracting these parameters is decreased by a factor of 60with respect to exact full-likelihood analyses. The results obtainedshow no tension with the flat Λ cold dark matter (ΛCDM)cosmological paradigm. By comparing with the full-likelihood exactanalysis with fixed dark energy models, on one hand we demonstrate thatthe double-probe method provides robust cosmological parameterconstraints that can be conveniently used to study dark energy models,and on the other hand we provide a reliable set of measurements assumingdark energy models to be used, for example, in distance estimations. Weextend our study to measure the sum of the neutrino mass using differentmethodologies, including double-probe analysis (introduced in thisstudy), full-likelihood analysis and single-probe analysis. Fromfull-likelihood analysis, we obtain Σm_ν < 0.12(68 per cent), assuming ΛCDM and Σm_ν <0.20 (68 per cent) assuming owCDM. We also find that there is degeneracybetween observational systematics and neutrino masses, which suggeststhat one should take great care when estimating these parameters in thecase of not having control over the systematics of a given sample.

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