Galaxy clustering, CMB and supernova data constraints on phi CDM model with massive neutrinos

摘要

We investigate a scalar field dark energy model (i.e., phi CDM model) with massive neutrinos, where the scalar field possesses an inverse power-law potential, i.e., V(phi) alpha phi(-alpha) (alpha > 0). We find that the sum of neutrino masses Sigma m(nu) has significant impacts on the CMB temperature power spectrum and on the matter power spectrum. In addition, the parameter alpha also has slight impacts on the spectra. A joint sample, including CMB data from Planck 2013 and WMAP9, galaxy clustering data from WiggleZ and BOSS DR11, and JLA compilation of Type Ia supernova observations, is adopted to confine the parameters. Within the context of the phi CDM model under consideration, the joint sample determines the cosmological parameters to high precision: the angular size of the sound horizon at recombination, the Thomson scattering optical depth due to reionization, the physical densities of baryons and cold dark matter, and the scalar spectral index are estimated to be theta(*) = (1.0415(0.0011)(+0.0012)) x 10(-2), tau = 0.0914(0.0242)(+0.0266), Omega(b)h(2)= 0.0222 +/- 0.0005, Omega(c)h(2) = 0.1177 +/- 0.0036, and n(s) = 0.9644(-0.0119)(+0.0118), respectively, at 95% confidence level (CL). It turns out that alpha < 4.995 at 95% CL for the phi CDM model. And yet, the Lambda CDM scenario corresponding to alpha = 0 is not ruled out at 95% CL. Moreover, we get Sigma m(nu) < 0.262 eV at 95% CL for the phi CDM model, while the corresponding one for the Lambda CDM model is Sigma m(nu) < 0.293 eV. The allowed scale of Sigma m(nu) in the phi CDM model is a bit smaller than that in the Lambda CDM model. It is consistent with the qualitative analysis, which reveals that the increases of alpha and Sigma m(nu) both can result in the suppression of the matter power spectrum. As a consequence, when alpha is larger, in order to avoid suppressing the matter power spectrum too much, the value of Sigma m(nu) should be smaller. (C) 2015 The Authors. Published by Elsevier B.V.