Halving and Doubling: Boosting the Detection of Relativistic Effects in the Galaxy Bispectrum with Optimal Subsample Selection

TL;DR

This paper introduces an optimal subsample selection method that significantly improves the detection of relativistic effects in the galaxy bispectrum, making them observable with current galaxy surveys like DESI.

Contribution

The authors propose a novel sampling strategy that enhances the detectability of relativistic effects in the galaxy bispectrum by splitting data into faint and bright subsamples and combining their auto-bispectra.

Findings

Detectability of relativistic effects is improved with the new sampling method.

The strategy enables first-time detection of these effects in surveys like DESI.

Sampling enhances the signal-to-noise ratio for relativistic signatures.

Abstract

On the scale of the cosmic horizon, signatures that are unique to general relativity are concealed within the statistics of the large scale distribution of galaxies. These were thought to be beyond the reach of all but the most ambitious galaxy surveys, as they are substantially suppressed relative to standard redshift-space distortions. We show that the detectability of these higher-order relativistic effects can be dramatically enhanced by a sampling strategy that splits a galaxy catalogue into faint and bright subsamples and then combines their auto-bispectra. For current surveys such as DESI, this implies that this new signal will be detectable for the first time using our new strategy.