| The circumgalactic medium (CGM) presents a significant baryon reservoir for sustaining star formation and provides insights into the inflows, outflows, and feedback history of galaxies. Star-forming dwarf galaxies, with their shallow potential wells, are predicted to drive metal-enriched gas into the CGM. Therefore, a census of CGM around dwarf galaxies can provide insights into the feedback mechanisms at play. We present multiphase absorption-line measurements in quasar sightlines adjacent to 126 isolated dwarf galaxies with a median stellar mass of M_*/M_sun ≈ 8.4 from the Cosmic Ultraviolet Baryon Survey (CUBS). This survey uses HST absorption spectroscopy to access a range of ion transitions from 0.077 < z < 0.73 such as the Lyman-series transitions for HI, as well as a range of multiphase metal lines including low (e.g. CII, SiII), intermediate (e.g. CIII, SiIII) and high (e.g. OVI) ions. We combine this with deep spectroscopic galaxy surveys to discover faint galaxies and characterize their environment, resulting in an 8-fold increase in the number of star-forming field dwarf galaxies with multiphase, multi-element absorption line measurements. Using our enhanced sample, we measured the HI and OVI covering fractions and ion masses beyond the virial radius, as well as the kinematic distribution of absorbers. We find a lower number of detections of low-ionization metal ions with increasing distance from the galaxies, with no detections outside the virial radius, though higher ions such as OVI are more common. We infer that the oxygen within the OVI-bearing phase of the CGM/IGM accounts for 60% of the oxygen budget from star-formation, and the total M_gas of the CGM represents 12% of the baryon budget. Moreover, the kinematic data suggests that a relatively small portion of the OVI gas is unbound and likely ejected through feedback processes. |
