The UV properties of E+A galaxies: constraints on feedback-driven quenching of star formation

TL;DR

This study investigates the ultraviolet properties of E+A galaxies, revealing their recent starburst activity, the correlation between luminosity and star formation rate, and the role of AGN and supernova feedback in quenching star formation.

Contribution

It provides the first large-scale UV analysis of E+A galaxies and links quenching efficiency to galaxy mass and feedback mechanisms, highlighting the role of AGN and supernovae.

Findings

High starburst fraction (20-60%) in E+A galaxies within last Gyr.

Luminosity correlates with star formation rate, with more luminous galaxies having higher SFRs.

Quenching efficiency varies with galaxy mass, linked to feedback from AGN and supernovae.

Abstract

We present the first large-scale study of E+A (post-starburst) galaxies that incorporates photometry in the ultraviolet (UV) wavelengths. We find that the starburst that creates the E+A galaxy typically takes place within the last Gyr and creates a high fraction (20-60 percent) of the stellar mass in the remnant over a short timescale (< 0.1 Gyrs). We find a tight correlation between the luminosity of our E+A galaxies and the implied star formation rate (SFR) during the starburst. While low-luminosity E+As (M(z) > -20) exhibit implied SFRs of less than 50 solar masses per year, their luminous counterparts (M(z) < -22) shows SFRs greater than 300 and as high as 2000 solar masses per year, suggesting that luminous and ultra-luminous infrared galaxies in the low-redshift Universe could be the progenitors of massive nearby E+A galaxies. We perform a comprehensive study of the characteristics of the quenching that truncates the starburst in E+A systems.We find that, for galaxies less massive than 10^10 MSun, the quenching efficiency decreases as the galaxy mass increases. However, for galaxies more massive than 10^10 MSun, this trend is reversed and the quenching efficiency increases with galaxy mass. Noting that the mass threshold at which this reversal occurs is in excellent agreement with the mass above which AGN become significantly more abundant in nearby galaxies, we use simple energetic arguments to show that the bimodal behaviour of the quenching efficiency is consistent with AGN and supernovae (SN) being the principal sources of negative feedback above and below M ~ 10^10 MSun respectively. (abridged)