Model-independent versus model-dependent interpretation of the SDSS-III BOSS power spectrum: Bridging the divide

TL;DR

This paper introduces ShapeFit, a fast, model-independent method for analyzing galaxy survey data that effectively captures early- and late-time physics, matching the accuracy of traditional model-dependent techniques.

Contribution

ShapeFit is a novel, efficient approach that separates early- and late-time cosmological variables, improving analysis speed and systematic control in galaxy clustering studies.

Findings

ShapeFit matches the constraining power of model-dependent methods.

ShapeFit is approximately 30 times faster than traditional approaches.

ShapeFit provides better control over observational systematics.

Abstract

The traditional clustering analyses of galaxy redshift surveys compress the clustering data into a set of late-time physical variables in a model-independent way. This approach has recently been extended by an additional shape variable encoding early-time physics information. We apply this new technique, ShapeFit, to SDSS-III BOSS data and show that it matches the constraining power of alternative, model-dependent approaches, which directly constrain the model's parameters adopting a cosmological model ab-initio. ShapeFit is $\sim30$ times faster, model-independent, naturally splits early- and late-time variables, and enables a better control of observational systematics.