Starburst Galaxies in Their Last Billion Years: An H<i>δ</i> Absorption Line Selected Sample

Abstract In this paper, we focus on the study of starburst galaxies in their final billion years. Our galaxy selection is based solely on the presence of the H δ absorption line, which permits the later evolution of starburst galaxies to be traced, coinciding with the emergence of A-type stars in these galaxies. We propose a novel method that utilizes star formation rate and UVJ colors to classify galaxies in the sample, and use the spectral features to mark their stages of evolution. Our in-depth analysis of the Mg ii line indicates the substantial increase in the number of F- and G-type stars when a galaxy evolves from star-forming to quiescent phase. Furthermore, we identify active galactic nuclei in this sample to explore their roles in the later stage of the star formation history of galaxies.