Marvelous Metals: Surveying the Circumgalactic Medium of Simulated Dwarf Galaxies

Abstract Dwarf galaxies are uniquely sensitive to feedback processes and known to experience substantial mass and metal loss from their disks. Here, we investigate the circumgalactic medium (CGM) of 64 isolated dwarf galaxies ( 6.0 < log ( M * / M ⊙ ) < 9.5 ) at z = 0 from the Marvel-ous Dwarfs and Marvelous Massive Dwarfs simulations. Our galaxies produce column densities broadly consistent with current observations. We investigate these column densities in the context of mass and metal retention rates, and CGM physical properties. We find 48% ± 11% of all baryons within R 200 c reside in the CGM, with ∼70% of CGM mass existing in a warm gas phase, 10 4.5 < T < 10 5.5 K, that dominates beyond r / R 200 c ∼ 0.5. The warm and cool (10 4.0 < T < 10 4.5 K) gas phases each retain 5%–10% of metals formed by the dwarf galaxy. The significant fraction of mass and metals residing in the warm CGM phase provides an interpretation for the lack of z ∼ 0 low ion detections beyond b / R 200 c ∼ 0.5, as the majority of mass in this region exists in higher ions. We find a weak correlation between galaxy mass and total CGM metal retention despite the fraction of metals lost from the halo increasing from ∼10% to >40% toward lower masses. Our findings highlight the CGM (particularly its warm phase) as a key reservoir of mass and metals for dwarf galaxies across stellar masses, underscoring its importance in understanding the baryon cycle in the low-mass regime. Finally, we provide individual simulated galaxy properties and quantify the fraction of UV-observable mass to support future observational programs aimed at performing a metal budget around dwarf galaxies.