Evidence for baryon acoustic oscillations from galaxy-ellipticity correlations

The Baryon Acoustic Oscillations (BAO) feature in the clustering of galaxies or quasars provides a ``standard ruler" for distance measurements in cosmology. In this work, we report a $2\sim3\sigma$ signal of the BAO dip feature in the galaxy density-ellipticity (GI) cross-correlation functions using the spectroscopic sample of the Baryon Oscillation Spectroscopic Survey (BOSS) CMASS, combined with the deep DESI Legacy Imaging Surveys for precise galaxy shape measurements. We measure the GI correlation functions and model them using the linear alignment model. We constrain the distance $D_V/r_{\mathrm{d}}$ to redshift $0.57$ to a precision of $3\sim5\%$, depending on the details of modeling. The GI measurement reduces the uncertainty of distance measurement by $\sim10\%$ on top of that derived from the galaxy-galaxy (GG) correlation. More importantly, for future large and deep galaxy surveys, the independent GI measurements can help sort out the systematics in the BAO studies.Comment: Main text 3 figures + supplementary 5 figures. Published in Nature Astronom