Strong [O iii] λ5007 Compact Galaxies Identified from SDSS DR16 and Their Scaling Relations

Green-pea galaxies are a special class of star-forming compact galaxies with strong [O iii]λ5007 and considered as analogs of high-redshift Lyα-emitting galaxies and potential sources for cosmic reionization. In this paper, we identify 76 strong [O iii]λ5007 compact galaxies at z < 0.35 from DR16 of the Sloan Digital Sky Survey. These galaxies present relatively low stellar mass, high star-formation rate, and low metallicity. Both the star-forming main-sequence (SFMS) relation and mass–metallicity relation (MZR) are investigated and compared with green-pea and blueberry galaxies collected from literature. It is found that our strong [O iii] λ5007 compact galaxies share common properties with those compact galaxies with extreme star formation and show distinct scaling relations in respect to those of normal star-forming galaxies at the same redshift. The slope of SFMS is higher, indicates that strong [O iii]λ5007 compact galaxies might grow faster in stellar mass. The lower MZR implies that they may be less chemically evolved and hence on the early stage of star formation. A further environmental investigation confirms that they inhabit relatively low-density regions. Future large-scale spectroscopic surveys will provide more details on their physical origin and evolution.