Five E+A (post-starburst) galaxies as Brightest Cluster Galaxies

TL;DR

This study identifies five post-starburst Brightest Cluster Galaxies (BCGs) out of over 8,800, revealing rare instances of recent star formation in these typically quiescent galaxies, with less intense features than in general galaxies.

Contribution

First identification of E+A (post-starburst) features in BCGs, showing that such galaxies can have recent but not violent star formation episodes.

Findings

5 out of 8,812 BCGs are E+A galaxies

E+A features are less significant than in typical galaxies

Star formation in these BCGs was not very violent

Abstract

Brightest Cluster Galaxies (BCGs) are mostly elliptical galaxies and very rarely have prominent star formation. We found that five out of 8,812 BCGs are E+A (i.e. post-starburst) galaxies, having the H$\delta$~absorption line with an equivalent width $>2.5\AA$ and no distinct emission lines in [O II] and H$\alpha$. The E+A features we identified from the BCGs for the first time are not as significant as those in general galaxies, indicating that historically the star formation were not very violent.