An algorithm to locate the centers of baryon acoustic oscillations

Abstract

Context. The cosmic structure formed from baryon acoustic oscillations (BAO) in the early universe is imprinted in the galaxy distribution observable in large-scale surveys and is used as a standard ruler in contemporary cosmology. Typically, BAOs are detected as a preferential length scale in two-point statistics, which gives little information about the location of the BAO structures in real space. Aims. The aim of the algorithm described in this paper is to find probable centers of BAOs in the cosmic matter distribution. Methods. The algorithm convolves the three-dimensional distribution of matter density with a spherical shell kernel of variable radius placed at different locations. The locations that correspond to the highest values of the convolution correspond to the probable centers of BAOs. This method is realized in an open-source, computationally efficient algorithm. Results. We describe the algorithm and present the results of applying it to the SDSS DR9 CMASS survey and associated mock catalogs. Conclusions. A detailed performance study demonstrates the ability of the algorithm to locate BAO centers and in doing so presents a novel detection of the BAO scale in galaxy surveys.