GLOW survey maps HI and stellar data for 37 nearby low-mass galaxies to track oxygen retention

The team processed archival VLA HI cubes, HST optical imaging for color-magnitude diagrams, and Spitzer imaging for stellar mass estimates, supplementing with new ground-based optical data and TRGB distances where gaps existed. Direct-method oxygen abundances and N/O ratios were compiled from the literature and new spectroscopy. This yields the first structural mapping of HI profiles against stellar mass and star-formation rate for the sample. Agreement between CMD-derived and 3.6-micron stellar masses validates the mass-to-light assumptions used in larger surveys.

Low-mass galaxies are expected to lose a large fraction of their metals via winds, yet the GLOW sample shows retained oxygen fractions that vary systematically with rotation velocity and local density. These trends challenge simple outflow prescriptions in cosmological simulations that over-predict metal loss below 10^8 solar masses. The dataset directly constrains the production-distribution-retention cycle that models must reproduce before they can be trusted at higher redshift.

The next GLOW papers will combine these maps with UV absorption-line measurements of outflowing gas to close the metal budget on a per-galaxy basis. If the retained oxygen fraction remains above 30 percent across the sample, current feedback efficiencies in IllustrisTNG and EAGLE will require downward revision for dwarf regimes.

Limitations include the modest sample size and reliance on heterogeneous literature abundances; expanding to 100 galaxies with uniform IFU spectroscopy would tighten the constraints.