Large-Scale Structure of the Universe as a Cosmic Standard Ruler

TL;DR

This paper introduces a method to use the large-scale structure of the universe as a cosmic standard ruler, leveraging galaxy distribution patterns to measure the universe's expansion history and cosmological parameters.

Contribution

It proposes using the genus statistic of galaxy topology as a robust standard ruler resistant to non-linear effects, enabling precise constraints on the universe's expansion history.

Findings

Genus measure is resistant to non-linear gravitational effects.

Galaxy distribution patterns can serve as reliable standard rulers.

Method constrains cosmological parameters effectively.

Abstract

We propose to use the large-scale structure of the universe as a cosmic standard ruler, based on the fact that the pattern of galaxy distribution should be maintained in the course of time on large scales. By examining the scale-dependence of the pattern in different redshift intervals it is possible to reconstruct the expansion history of the universe, and thus to measure the cosmological parameters governing the expansion of the universe. The features in the galaxy distribution that can be used as standard rulers include the topology of large-scale structure and the overall shapes of galaxy power spectrum and correlation function. The genus, being an intrinsic topology measure, is resistant against the non-linear gravitational evolution, galaxy biasing, and redshift-space distortion effects, and thus is ideal for quantifying the primordial topology of the large-scale structure. The expansion history of the universe can be constrained by comparing among the genus measured at different redshifts. In the case of initially Gaussian fluctuations the genus accurately recovers the slope of the primordial power spectrum near the smoothing scale, and the expansion history can be constrained by comparing between the predicted and measured genus.