H{\alpha} Dots: Direct-Method Metal Abundances of Low-Luminosity Star-Forming Systems

TL;DR

This study uses spectroscopic data from the Hα Dots survey to determine metal abundances in low-luminosity star-forming systems, revealing flattened metallicity relations and providing insights into early galaxy formation.

Contribution

It introduces a new method for identifying and analyzing low-luminosity star-forming galaxies, with direct metallicity measurements and analysis of their scaling relations.

Findings

Flattened luminosity-metallicity relation in low-luminosity systems

Flattened stellar mass-metallicity relation in these regimes

Hα Dots survey effectively identifies star-forming dwarf galaxies

Abstract

Utilizing low-luminosity star-forming systems discovered in the H$\alpha$ Dots survey, we present spectroscopic observations undertaken using the KPNO 4m telescope for twenty-six sources. With determinations of robust, "direct"-method metal abundances, we examine the properties of these dwarf systems, exploring their utility in characterizing starburst galaxies at low luminosities and stellar masses. We find that the H$\alpha$ Dots survey provides an effective new avenue for identifying star-forming galaxies in these regimes. In addition, we examine abundance characteristics and metallicity scaling relations with these sources, highlighting a flattening of both the luminosity-metallicity ($L$-$Z$) and stellar mass-metallicity ($M_{*}$-$Z$) relation slopes in these regimes as compared with those utilizing samples covering wider respective dynamic ranges. These local, accessible analogues to the kinds of star-forming dwarfs common at high redshift will help shed light on the building blocks which assembled into the massive galaxies common today.