Evidence for baryon acoustic oscillations from galaxy-ellipticity correlations

Baryon acoustic oscillations from the early Universe are imprinted in the large-scale structure, providing a cosmic expansion ruler. A comparison of the shapes and positions of galaxies can yield an independent measure of these primordial oscillations. The baryon acoustic oscillation feature in the clustering of galaxies or quasars provides a 'standard ruler' for distance measurements in cosmology. In this work, we report a 2-3 sigma signal of the baryon acoustic oscillation dip feature in the galaxy density-ellipticity cross-correlation functions using the spectroscopic sample of the Baryon Oscillation Spectroscopic Survey CMASS, combined with the deep Dark Energy Spectroscopic Instrument Legacy Imaging Surveys for precise galaxy shape measurements. We measure the galaxy-ellipticity correlation functions and model them using the linear alignment model. We constrain the distance D-V/r(d) to redshift 0.57 to a precision of 3-5%, depending on the details of modelling. The galaxy-ellipticity measurement reduces the uncertainty of distance measurement by similar to 10% on top of that derived from the galaxy-galaxy correlation. More importantly, for future large and deep galaxy surveys, the independent galaxy-ellipticity measurements can help sort out the systematics in the baryon acoustic oscillation studies.