Beating non-linearities: improving the Baryon Acoustic Oscillations with the linear point

TL;DR

The paper introduces the 'linear point' as a robust, non-linear-insensitive standard ruler in the correlation function for improved cosmological measurements, with promising preliminary data results.

Contribution

It identifies a new scale, the linear point, that remains stable against non-linear effects, enhancing the accuracy of cosmological distance and growth measurements.

Findings

The linear point is insensitive to non-linearities at 0.5% level.

The amplitude at the linear point is stable within a few percent.

Preliminary analysis of current data shows promising results.

Abstract

We propose a new way of looking at the Baryon Acoustic Oscillations in the Large Scale Structure clustering correlation function. We identify a scale s_LP that has two fundamental features: its position is insensitive to non-linear gravity, redshift space distortions, and scale-dependent bias at the 0.5% level; it is geometrical, i.e. independent of the power spectrum of the primordial density fluctuation parameters. These two properties together make s_LP, called the "linear point", an excellent cosmological standard ruler. The linear point is also appealing because it is easily identified irrespectively of how non-linearities distort the correlation function. Finally, the correlation function amplitude at s_LP is similarly insensitive to non-linear corrections to within a few percent. Hence, exploiting the particular Baryon features in the correlation function, we propose three new estimators for growth measurements. A preliminary analysis of s_LP in current data is encouraging.