What question did this study set out to answer?

This research aims to determine the growth rate of the universe using galaxy intrinsic alignments.

March 1, 2023Open Access

First Constraints on Growth Rate from Redshift-space Ellipticity Correlations of SDSS Galaxies at 0.16 < z < 0.70

Key Points

This research aims to determine the growth rate of the universe using galaxy intrinsic alignments.
Measured galaxy density-intrinsic ellipticity cross-correlation and autocorrelation functions over redshift range 0.16 to 0.7.
Analyzed luminous red galaxies (LRGs), LOWZ, and CMASS samples from the SDSS and SDSS-III BOSS survey.
Combined intrinsic alignment statistics with conventional galaxy clustering statistics to obtain constraints.
Growth rate determined as f σ8 = 0.5196 -0.0354 +0.0352 with clustering-only analysis at 68% confidence level.
Improved constraints using intrinsic alignments yield f σ8 = 0.5322 -0.0291 +0.0293, indicating a 19% enhancement.
Improvements of 10% and 3.5% for LOWZ and CMASS samples respectively, aligning with general relativity predictions.

Abstract

Abstract We report the first constraints on the growth rate of the universe, f ( z ) σ 8 ( z ), with intrinsic alignments (IAs) of galaxies. We measure the galaxy density-intrinsic ellipticity cross-correlation and intrinsic ellipticity autocorrelation functions over 0.16 f σ 8 = 0.5196 − 0.0354 + 0.0352 (68% confidence level) from the clustering-only analysis and f σ 8 = 0.5322 − 0.0291 + 0.0293 with clustering and IA, meaning 19% improvement. The constraint is in good agreement with the prediction of general relativity, f σ 8 = 0.4937 at z = 0.34. For LOWZ and CMASS samples, the improvement of constraints on f σ 8 is found to be 10% and 3.5%, respectively. Our results indicate that the contribution from IA statistics for cosmological constraints can be further enhanced by carefully selecting galaxies for a shape sample.

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