Do most early-type galaxies end with a terminating burst?

Determine whether most early-type (quiescent elliptical) galaxies end their star formation histories with a final, self-enriching burst of star formation immediately prior to quenching, as proposed to explain elevated light-weighted [Mg/Fe] ratios in comparison to one-zone galactic chemical evolution models with empirically motivated yields.

Background

The paper finds that smooth one-zone galactic chemical evolution models calibrated to Milky Way–motivated supernova yields underpredict the observed ⟨[Mg/Fe]⟩ of elliptical galaxies by approximately 0.05–0.1 dex. A proposed resolution is that many ellipticals experience a terminating burst of star formation that self-enriches the interstellar medium with core-collapse supernova products just before quenching, thereby boosting ⟨[Mg/Fe]⟩ and reducing the light-weighted age.

While post-starburst populations (E+A/K+A) demonstrate that some galaxies undergo such bursts, the prevalence of a final, self-enriching burst across the broader early-type population is not established. The authors highlight this uncertainty and suggest that targeted population synthesis of late star formation episodes could test the hypothesis.