Clipping the Cosmos: The Bias and Bispectrum of Large Scale Structure

TL;DR

This paper introduces a novel method to extract more information from galaxy bispectrum data in large-scale structure surveys, significantly extending the usable scale range and improving parameter constraints, with potential applications in testing gravity theories.

Contribution

The authors present a new technique that leverages the bispectrum beyond traditional perturbation theory limits, enhancing the analysis of large-scale structure data.

Findings

Extends the perturbation theory validity from k_max ~ 0.1 h/Mpc to ~ 0.7 h/Mpc.

Improves galaxy bias measurements significantly.

Potential to probe growth rate and test modified gravity theories.

Abstract

A large fraction of the information collected by cosmological surveys is simply discarded to avoid lengthscales which are difficult to model theoretically. We introduce a new technique which enables the extraction of useful information from the bispectrum of galaxies well beyond the conventional limits of perturbation theory. Our results strongly suggest that this method increases the range of scales where the relation between the bispectrum and power spectrum in tree-level perturbation theory may be applied, from k_max ~ 0.1 h/Mpc to ~ 0.7 h/Mpc. This leads to correspondingly large improvements in the determination of galaxy bias. Since the clipped matter power spectrum closely follows the linear power spectrum, there is the potential to use this technique to probe the growth rate of linear perturbations and confront theories of modified gravity with observation.