Galaxy evolution in different environments along redshift within the local universe z < 0.8

Abstract

This study presents the evolution of the galaxies in different matter density along redshift within the local universe. A sample of 702,352 galaxies was collected from the Sloan Digital Sky Survey (SDSS). Under the limitation of the spectroscopic data, the appropriate photometric redshift was used to represent the spectroscopic redshift in the range of 0.0 ≤ z ≤ 0.8. Number density of galaxies, galaxy's colors, and star formation activities are considered to describe the evolution of galaxies. In summary, the number density is not clearly different although the Dec and RA of the sky areas are disparate, but it steeply declines along the redshift direction. Considering the number density together with galaxies' Hα emission line from spectroscopic data, we find that both equivalent of hydrogen alpha and Hα flux tend to decrease along the redshift, similar to the decreasing trend of the number density. Furthermore, the galaxy color trend is found to be redder as a function of the redshift for the magnitude range of -19 ≤ Mg ≤ -17. It implies that the overview of the star formation activity of the fainter galaxies at the lower redshift tend to show higher than the ones at higher redshift.