Environmental Dependence of Galaxy Properties in the Southern GAMA Regions

Abstract Using data from the Galaxy and Mass Assembly (GAMA) survey, we investigate how galaxy properties correlate with the local environment, focusing on its two southern regions (G02 and G23) that have not previously been examined in this context. We employ two-point and marked correlation functions to quantify the environmental dependence of galaxy color, stellar mass, luminosity across the u , g , r , J , and K bands, as well as star formation rate (SFR) and specific star formation rate (sSFR). Our results show that u − r and g − r colors are most strongly correlated with local overdensity, followed by stellar mass. The SFR and sSFR exhibit a clear inverse relationship with environmental density, consistent with the trend observed for u -band luminosity, which traces young stellar populations. The galaxies brighter in the g , J , and K bands preferentially inhabit denser regions. We interpret the environmental dependence of color using halo occupation distribution (HOD) modeling. The HOD modeling indicates that red galaxies trace dense environments more strongly than blue galaxies, exhibiting significantly higher satellite fractions and occupying more massive halos. We demonstrate that both redshift and stellar mass incompleteness systematically affect clustering measurements, generally enhancing the observed environmental dependence. Comparing our measurements from the southern regions with those from the equatorial GAMA regions, we find that the overall environmental trends remain consistent. The measured correlations provide key constraints for models of galaxy assembly across mass and environment, while environmental trends in color and near-infrared luminosity trace stellar mass growth and quenching with redshift.