Ageing and Quenching: Influence of Galaxy Environment and Nuclear Activity in Transition Stage

TL;DR

This study investigates how galaxy environment and nuclear activity influence galaxy ageing and quenching during transition stages, revealing environment dependence for ageing but not for quenching.

Contribution

It provides new insights into the environmental and nuclear activity influences on galaxy evolution during transition stages using SDSS data.

Findings

Ageing galaxies show significant environmental dependence.

Quenching galaxies do not show environmental dependence.

Star formation and colour-stellar mass relations are affected differently for ageing and quenching galaxies.

Abstract

This study aims to investigate whether the environment and the nuclear activity of a particular galaxy influence the ageing and quenching at the transition stage of the galaxy evolution using the volume-limited sample constructed from the twelve release of the Sloan Digital Sky Survey. To this end, the galaxies were classified into isolated and non-isolated environments and then each subsample was further classified according to their nuclear activity using the WHAN diagnostic diagram, and ageing diagram to obtain ageing and quenching galaxies. The ageing and quenching galaxies at the transition stage were selected for the rest of the analysis. Using the star formation rate and the $u-r$ colour-stellar mass diagrams, the study revealed a significant change of $0.03$ dex in slope and $0.30$ dex in intercept for ageing galaxies and an insignificant change of $0.02$ dex in slope and $0.12$ dex in intercept of the star formation main sequence between isolated and non-isolated quenching galaxies. Further, a more significant change in the number of ageing galaxies above, within and below the main sequence and the green valley was observed. On the other hand, an insignificant change in the number of quenching galaxies above, within and below the main sequence and the green valley was observed. The study concludes that ageing depends on the environment and the dependence is influenced by the nuclear activity of a particular galaxy while quenching does not depend on the environment and this independence is not influenced by the nuclear activity.