Effects of redshift, mass and environment on the concentration index

Abstract The morphological classification of galaxies is crucial for understanding their formation and evolution over time. There are various galaxy parameters, such as structural features, light profiles, and the concentration index (Cr ) that serve as proxies for galaxy morphological types that can be used to classify galaxies effectively. These galaxy parameters have been proposed for classifying galaxies in the large galaxy samples, where visual classification becomes labor-intensive and impractical. This work report on the the effect of fundamental galaxy parameters; redshift, environment and mass on the use of concentration index tool for classifying galaxies. The archival data for this work was obtained from the Sloan Digital Sky Survey - AMIGA catalog SDSS-DR 16. The low density population constrained to a redshift range 0.005 ≤ z ≤ 0.080 and r-band magnitudes range 11 ≤ Mr ≤ 15.7, while the dense environment sample obtained from the Coma Cluster for sources within 3000 ≤ cz ≤ 10500 kms−1 at a redshift range of 0.01 ≤ z ≤ 0.035. To study the effect of redshift on the concentration index, the low density galaxy sample (SIG) constrained by median stellar mass 10 ≤ log M⊙ ≤ 12 (3148 galaxies) was used. A fit to the derived Cr showed that concentration index increases with redshift. Similarly, to investigated the effect of stellar mass on the Cr of galaxies, SIG population at a redshift range of 0.02 ≤ z ≤ 0.04 was considered and from the Cr - stellar mass fit, the Cr is seen to be proportional to stellar mass. To investigate the effect of galactic environment, the galaxies in both low-density and high-density population were constrained to a mass range of 10 ≤ ≤ log M⊙ ≤ 12 and a redshift range of 0.02 ≤ z ≤ 0.04. A fit to the derived Cr values against the galaxy environments showed that Cr values increases from less-dense to high-dense environments. These trends indicate the importance investigating the effect of galaxy physical parameters on the concentration index of the galaxies.