2015/06/30 by Pablo Arnalte-Mur, Patricio Vielva, Vicent J. Martínez +3 · 1 citation
Physics and Astronomy · #A priori and a posteriori #Astronomy and Astrophysical Research #Bayesian probability #Cosmology and Gravitation Theories #Dark energy #Dark matter #Density contrast #Galaxies: Formation, Evolution, Phenomena #Galaxy #Inference #Number density #Probability density function #astro-ph.CO
paper · pdf · doi:10.1088/1475-7516/2016/03/005
published as JCAP03(2016)005 · 25 pages, 9 figures, 2 tables. v2: Substantial revision, adding the joint constraints with σ_8 and testing with Las Damas mocks. Matches version accepted for publication in JCAP
arxiv created 2016/02/16 · openalex publication_date 2016/03/04 · arxiv updated 2016/03/08 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present a full description of the N-probability density function of the galaxy number density fluctuations. This N-pdf is given in terms, on the one hand, of the cold dark matter correlations and, on the other hand, of the galaxy bias parameter. The method relies on the assumption commonly adopted that the dark matter density fluctuations follow a local non-linear transformation of the initial energy density perturbations. The N-pdf of the galaxy number density fluctuations allows for an optimal estimation of the bias parameter (e.g., via maximum-likelihood estimation, or Bayesian inference if there exists any a priori information on the bias parameter), and of those parameters defining the dark matter correlations, in particular its amplitude (σ 8 ). It also provides the proper framework to perform model selection between two competitive hypotheses. The parameters estimation capabilities of the N-pdf are proved by SDSS-like simulations (both, ideal log-normal simulations and mocks obtained from Las Damas simulations), showing that our estimator is unbiased. We apply our formalism to the 7th release of the SDSS main sample (for a volume-limited subset with absolute magnitudes M r ⩽ −20). We obtain = 1.193 ± 0.074 and 8 = 0.862 ± 0.080, for galaxy number density fluctuations in cells of the size of 30 h −1 Mpc. Different model selection criteria show that galaxy biasing is clearly favoured.