The Role of Active Galactic Nuclei in the Quenching of Massive Galaxies in the SQuiGGLE Survey

TL;DR

This study investigates the prevalence of active galactic nuclei in massive post-starburst galaxies at z~0.7, revealing that nuclear activity correlates more with stellar age and gas availability than with stellar mass.

Contribution

It provides new insights into the relationship between nuclear activity, stellar age, and gas content in post-starburst galaxies at intermediate redshifts.

Findings

Radio activity weakly depends on stellar mass

Optical activity is higher in younger galaxies

Nuclear activity correlates with gas availability

Abstract

We study the incidence of nuclear activity in a large sample of massive post-starburst galaxies at z~0.7 selected from the Sloan Digital Sky Survey, and identify active galactic nuclei based on radio continuum and optical emission lines. Over our mass range of 10^10.6-10^11.5 Msun, the incidence of radio activity is weakly dependent on stellar mass and independent of stellar age, while radio luminosity depends strongly on stellar mass. Optical nuclear activity incidence depends most strongly on the Dn4000 line index, a proxy for stellar age, with an active fraction that is ~ten times higher in the youngest versus oldest post-starburst galaxies. Since a similar trend is seen between age and molecular gas fractions, we argue that, like in local galaxies, the age trend reflects a peak in available fueling rather than feedback from the central black hole on the surrounding galaxy.