Mass-dependent chemical enrichment sequences of SDSS star-forming galaxies out to z~0.3 revealed by direct O & Ar abundances

TL;DR

This study analyzes SDSS star-forming galaxies up to z~0.3, revealing mass-dependent chemical enrichment sequences through direct O and Ar abundance measurements, supporting galaxy chemical evolution models.

Contribution

First direct measurement of mass-dependent chemical enrichment sequences in star-forming galaxies using O and Ar abundances from SDSS data.

Findings

Higher and lower mass SFGs trace distinct sequences in the log(O/Ar) vs 12+log(Ar/H) plane.

Sequences align with galaxy chemical evolution models involving supernovae.

Demonstrates universality of chemical enrichment patterns across galaxy masses.

Abstract

Individual stars in the Milky Way (MW) and its satellites have been shown to trace galaxy stellar mass dependent sequences in the $\alpha$-abundance ([$\alpha$/Fe]) vs metallicity ([Fe/H]) plane. Testing the universality of such sequences has been elusive as deep absorption-line spectra required for [$\alpha$/Fe] and [Fe/H] measurements beyond the local group are mostly limited to integrated light from nearby, relatively high-mass, early-type galaxies. However, analogous to [$\alpha$/Fe] vs [Fe/H] for stars, we now have log(O/Ar) vs 12+log(Ar/H) for the integrated nebular light of star-forming galaxies (SFGs). From Sloan-Digital Sky Survey (SDSS) observations of $\sim3000$ SFGs out to z$\sim0.3$, where we directly determined O & Ar abundances, we obtain for the first time the distribution of an ensemble of SFGs in the log(O/Ar) vs 12+log(Ar/H) plane. We show that higher (<M$\rm_{*}$>$\sim2.6\times10^9$M$_{\odot}$) and lower mass (<M$\rm_{*}$>$\sim1.7\times10^7$M$_{\odot}$) SFGs clearly trace distinct mass dependent sequences in this plane. Such sequences are consistent with expectations from galaxy chemical evolution (GCE) models that are driven primarily by the interplay of core-collapse and Type Ia supernovae.