Cosmological parameters from the BOSS galaxy power spectrum

Abstract

We present cosmological parameter measurements from the publicly available Baryon Oscillation Spectroscopic Survey (BOSS) data on anisotropic galaxy clustering in Fourier space. Compared to previous studies, our analysis has two main novel features. First, we use a complete perturbation theory model that properly takes into account the non-linear effects of dark matter clustering, short-scale physics, galaxy bias, redshift-space distortions, and large-scale bulk flows. Second, we employ a Markov-Chain Monte-Carlo technique and consistently reevaluate the full power spectrum likelihood as we scan over different cosmologies. Our baseline analysis assumes minimal ΛCDM, varies the neutrino masses within a reasonably tight range, fixes the primordial power spectrum tilt, and uses the big bang nucleosynthesis prior on the physical baryon density ωb. In this setup, we find the following late-Universe parameters: Hubble constant H0=(67.9± 1.1) km s−1Mpc−1, matter density fraction Ωm=0.295± 0.010, and the mass fluctuation amplitude σ8=0.721± 0.043. These parameters were measured directly from the BOSS data and independently of the Planck cosmic microwave background observations. Scanning over the power spectrum tilt or relaxing the other priors do not significantly alter our main conclusions. Finally, we discuss the information content of the BOSS power spectrum and show that it is dominated by the location of the baryon acoustic oscillations and the power spectrum shape. We argue that the contribution of the Alcock-Paczynski effect is marginal in ΛCDM, but becomes important for non-minimal cosmological models.

Nonlinear perturbation theory extension of the Boltzmann code CLASS

“…Importantly, this method can be extended to the one-loop bispectrum and the two-loop power spectrum [24], which are not simple convolution integrals. 13 Keeping in mind these statistics as our eventual goal, we choose FFTLog for the implementation in CLASS. Another advantage of this algorithm is that it is very easy to implement, since it boils down to simple multiplications of the cosmologyindependent matrices with the cosmology-dependent vectors, which can be easily obtained from the linear matter power spectrum with FFT.…”

“…We leave the systematic derivation of all corrections of this order for future work. Let us stress that addition of this term can be important in order to fit the data or results from N-body simulations [13,16]. The full counterterm contribution is then given by P ctr;RSD ðz; k; μÞ ¼ P ctr;RSD;∇ 2 δ ðz; k; μÞ þ P ctr;RSD;∇ 4 z δ ðz; k; μÞ; ð2:17Þ…”

“…In the recent reanalyses of BOSS data, only the higher derivative counterterm is kept in Ref. [13], while the analysis of Ref. [75] uses the a 2 μ 2 k 2 contribution in its model.…”

“…Besides, we publicly release a custom-built BOSS galaxy power spectrum likelihood written for the Markov Chain Monte Carlo sampler MONTEPYTHON [6,12], which can be used for various cosmological analyses. It is worth stressing that CLASS-PT has been already applied to the analysis of the BOSS data [13][14][15], and used in a blind cosmology challenge based on a large-volume numerical simulation [16]. Moreover, in Ref.…”

Perturbation theory for the redshift-space matter power spectra after reconstruction

“…Bulk motion of galaxies associated with the growth of the large-scale structure generates the anisotropy in the redshift-space galaxy distribution, i.e., the redshiftspace distortion, which probes the growth rate of the large-scale structure and is useful to test General Relativity and modified gravity models [e.g., [25][26][27][28][29][30][31]. The full shape of the power spectrum also has fruitful information of cosmology [e.g., 32]. Upcoming spectroscopic galaxy surveys such as PFS [33], DESI [34], HETDEX [35], Euclid [36] and WFIRST [37] are expected to do precise cosmological studies to clarify the nature of dark matter and dark energy.…”