Galaxy Correlation Functions Provide a More Robust Cosmological Standard Ruler

Area of Science:

• Cosmology and extragalactic astronomy
• Galaxy evolution and large-scale structure

Background:

• Baryon Acoustic Oscillations (BAO) provide a standard ruler in cosmology.
• BAO peak location is sensitive to nonlinear effects and model-dependent analysis.

Purpose of the Study:

• To introduce and validate the 'linear point' in the galaxy two-point correlation function as a redshift-independent standard ruler.
• To measure cosmological distances using the linear point without relying on model-templates or reconstruction methods.

Main Methods:

• Analysis of the galaxy two-point correlation function from the BOSS DR12 LOWZ and CMASS samples.
• Identification and measurement of the characteristic length scale ('linear point').
• Combination of linear point measurements with Planck cosmic microwave background data to derive distance scales.

Main Results:

• The linear point is a robust cosmological standard ruler, constant in redshift and precise to 0.5% against nonlinear effects.
• Measured isotropic-volume distances: D_{V}(0.32) = 1264 ± 28 Mpc and D_{V}(0.57) = 2056 ± 22 Mpc.
• Results are consistent with existing BOSS Collaboration measurements.

Conclusions:

• The linear point effectively compresses all distance information from baryon acoustic oscillations into a single, reliable length scale.
• This method offers a simplified and robust approach to cosmological distance measurements.