Measuring the Universe with Galaxy Redshift Surveys

Abstract

Galaxy redshift surveys are one of the pillars of the current standard cosmological model and remain a key tool in the experimental effort to understand the origin of cosmic acceleration. To this end, the next generation of surveys aim at achieving sub-percent precision in the measurement of the equation of state of dark energy w(z) and the growth rate of structure f (z). This however requires comparable control over systematic errors, stressing the need for improved modelling methods. In this contribution we review at the introductory level some highlights of the work done in this direction by the Darklight project 7 . Supported by an ERC Advanced Grant, Darklight developed novel techniques for clustering analysis, which were tested through numerical simulations before being finally applied to galaxy data as in particular those of the recently completed VIPERS redshift survey. We focus in particular on: (a) advances on estimating the growth rate of structure from redshiftspace distortions; (b) parameter estimation through global Bayesian reconstruction of the density field from survey data; (c) impact of massive neutrinos on large-scale structure measurements. Overall, Darklight has contributed to paving the way for forthcoming high-precision experiments, such as Euclid, the next ESA cosmological mission. 8

The minimally extended Varying Speed of Light (meVSL)

“…Notably, the uniformity of the temperature of the cosmic microwave background (CMB) across different sky directions provides compelling evidence for the isotropy of the Universe on its grandest scales [31,32]. Moreover, the absence of a preferred center in the Universe suggests a corresponding homogeneity, reflected in the uniform distribution of matter across scales exceeding 100 million light years [33,34]. These observations lead to the formulation of the Cosmological Principle (CP), which asserts that the Universe exhibits uniformity from any vantage point in space and that all directions hold equal significance.…”

Review on Minimally Extended Varying Speed of Light Model

“…Evidence for isotropy is found in the uniformity of the cosmic microwave background (CMB) temperature [7,8]. Although proving homogeneity is more challenging, support comes from the uniform matter distribution on scales of more than 100 million light-years as large-scale structures (LSS) [9,10]. The ΛCDM model incorporates an expanding metric space, evidenced by the redshift of spectral lines in light from distant galaxies.…”