# The Linear Point: A cleaner cosmological standard ruler

## TL;DR

This paper introduces the 'linear point' as a robust, model-independent standard ruler in galaxy correlation functions, enabling precise cosmological distance measurements unaffected by non-linear effects.

## Contribution

It demonstrates that the linear point provides a stable, model-independent cosmological standard ruler, simplifying distance measurements from galaxy surveys without complex reconstructions.

## Key findings

- Measured the linear point in BOSS galaxy data.
- Derived consistent distance estimates with Planck constraints.
- Showed the linear point's robustness against non-linear effects.

## Abstract

We show how a characteristic length scale imprinted in the galaxy two-point correlation function, dubbed the "linear point", can serve as a comoving cosmological standard ruler. In contrast to the Baryon Acoustic Oscillation peak location, this scale is constant in redshift and is unaffected by non-linear effects to within $0.5$ percent precision. We measure the location of the linear point in the galaxy correlation function of the LOWZ and CMASS samples from the Twelfth Data Release (DR12) of the Baryon Oscillation Spectroscopic Survey (BOSS) collaboration. We combine our linear-point measurement with cosmic-microwave-background constraints from the Planck satellite to estimate the isotropic-volume distance $D_{V}(z)$, without relying on a model-template or reconstruction method. We find $D_V(0.32)=1264\pm 28$ Mpc and $D_V(0.57)=2056\pm 22$ Mpc respectively, consistent with the quoted values from the BOSS collaboration. This remarkable result suggests that all the distance information contained in the baryon acoustic oscillations can be conveniently compressed into the single length associated with the linear point.