Speaker
Description
This study involves the use of the friend-of-friend method on the volume-limited samples constructed from the Sloan Digital Sky Survey Data Release 12 (SDSS DR12) to classify the galaxies into isolated and non-isolated environments, hence to investigate the influence of the galaxy environment on the main sequence of star formation and colour bimodality. We classified the galaxies into the luminous volume-limited sample with $ -22.5\leq M_r \leq -20.5$ (mag) and the faint volume-limited sample with $-20.5 \leq M_r \leq -18.5$ (mag). Using the WHAN diagnostic diagram, we assigned the samples into star-forming, strong AGN, weak AGN, and retired galaxies based on their environment (isolated and non-isolated). The friend-of-friend method was successful in producing consistent results regarding the stellar mass-SFR and stellar mass-colour known relations. Apart from that, the decrease in the slope of the main sequence for star-forming galaxies by $0.04$ dex and intercept by $0.39$ dex for the luminous sample was observed, while for the faint sample, a decrease of $0.08$ dex in slope and $0.74$ dex in intercept was observed between isolated and non-isolated galaxies. A significant change on the number of galaxies between isolated and non-isolated galaxies within, above and below the main sequence by $4.84\%$, $9.70\%$, $11.97\%$ for the luminous sample, while for the faint sample by $5.75\%$, $7.96\%$, $10.00\%$ on average, respectively, was observed. A significant change in the number of galaxies in the blue cloud, green valley, and red sequence by $2.75\%$, $4.39\%$, $3.67\%$ for the luminous sample, while for the faint sample by $3.31\%$, $6.98\%$, $5.71\%$ on average, respectively, was observed. The study concludes that the galaxy environment influences the shaping and positioning of galaxies along the star formation main sequence and colour bimodality.
| Stream | Science |
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