# Geometrical compression: a new method to enhance the BOSS galaxy bispectrum monopole constraints

## TL;DR

This paper introduces a geometrical compression method for galaxy bispectrum data that significantly increases the number of measurements, reduces parameter uncertainties, and does not require prior covariance matrix computation, enhancing future survey analyses.

## Contribution

The paper presents a novel geometrical binning technique that compresses bispectrum data, improving parameter constraints without needing pre-computed covariance matrices.

## Key findings

- Increased bispectrum measurements by a factor of 23.
- Reduced credible interval widths for key parameters.
- Good agreement with existing maximal compression methods.

## Abstract

We present a novel method to compress galaxy clustering three-point statistics and apply it to redshift space galaxy bispectrum monopole measurements from BOSS DR12 CMASS data considering a $k$-space range of $0.03-0.12\,h/\mathrm{Mpc}$. The method consists in binning together bispectra evaluated at sets of wave-numbers forming closed triangles with similar geometrical properties: the area, the cosine of the largest angle and the ratio between the cosines of the remaining two angles. This enables us to increase the number of bispectrum measurements for example by a factor of $23$ over the standard binning (from 116 to 2734 triangles used), which is otherwise limited by the number of mock catalogues available to estimate the covariance matrix needed to derive parameter constraints. The $68\%$ credible intervals for the inferred parameters $\left(b_1,b_2,f,\sigma_8\right)$ are thus reduced by $\left(-39\%,-49\%,-29\%,-22\%\right)$, respectively. We find very good agreement with the posteriors recently obtained by alternative maximal compression methods. This new method does not require the a-priori computation of the data-vector covariance matrix and has the potential to be directly applicable to other three-point statistics (e.g. glaxy clustering, weak gravitational lensing, 21 cm emission line) measured from future surveys such as DESI, Euclid, PFS and SKA.