Accurate spectroscopic redshift estimation using nonnegative matrix factorization: Application to MUSE spectra

Accurate and automated galaxy redshift determinations are essential for maximizing the scientific return of spectroscopic surveys. In this paper, we propose a data-driven method to address this challenge. The method first learns a rest-frame representation of galaxy spectra using nonnegative matrix factorization (NMF). The method then reconstructs new spectra using this representation at different trial redshifts and identifies the correct redshift by selecting the one that minimizes the reconstruction error. We applied our method to galaxy spectra from the Multi Unit Spectroscopic Explorer (MUSE), covering redshifts from 0 to 6.7. Our method achieves an overall success rate of 93.7%. We demonstrate two applications: (i) the separation between true and false sources and (ii) the detection of blended sources from one-dimensional spectra. Our results demonstrate that NMF-based representations provide a powerful and physically motivated framework for redshift estimation in current and future large spectroscopic surveys.