Selecting Post-Starburst Galaxies Based on Star Formation History

TL;DR

This study introduces a new method for selecting post-starburst galaxies based on their star formation histories derived from integral field spectroscopy, revealing diverse PSB properties and challenging previous assumptions about their characteristics.

Contribution

The paper presents a novel SFH-based PSB selection method that is unbiased against AGN and uncovers a broader range of PSB galaxy types and spatial distributions.

Findings

Identified 107 PSB galaxies, mostly not previously recognized by other methods.

Found no significant Seyfert 2 PSB population, indicating rare strong AGN activity.

Discovered diverse PSB spatial configurations, including inside-out age gradients and ring-like structures.

Abstract

Post-StarBurst (PSB) galaxies are galaxies that have undergone a large burst of star formation followed by rapid quenching. Understanding their properties as a population can help us better understand how galaxies evolve to quiescence. This project aims to use Star Formation History (SFH) measurements from the Integral Field Spectroscopy (IFS) surveys MaNGA, CALIFA, and AMUSING++ processed with the Pipe3D analysis pipeline in order to select PSB galaxies as well as PSB regions in galaxies. Most PSB selection methods use cutoffs determined by spectral features, but in this work we introduce a new PSB selection method based directly on the property we are most interested in; inferred SFHs. IFS data allows us to probe a galaxy's star formation on a spatially resolved scale, enabling us to examine the size, shape, and location of PSB regions within a galaxy. We select 107 PSB galaxies, only 7 of which are among known PSBs selected by other methods. Unlike traditional PSB selection methods, our approach is not biased against Active Galactic Nuclei (AGN). Despite this, we still find no evidence for a significant Seyfert 2 PSB population, suggesting that strong AGN activity is uncommon throughout the PSB phase. Our spatially-resolved SFH selection identifies a wide range of galaxies, including globally quiescent elliptical galaxies with centrally-concentrated PSB spaxels, galaxies with ring-like PSB spaxels and a preference for inside-out age gradients (contrary to what has previously been observed in the literature), and galaxies with widespread PSB regions that have significant star formation elsewhere in the galaxy.