MUSEQuBES: The Column Density, Covering Fraction, Mass, and Environmental Dependence of Cool H  i Gas Around Low-Redshift Galaxies

Abstract We investigate cool H i gas traced by Lyman series absorption around 256 galaxies at z ≈ 0. 48 (median stellar mass, ₁₀~ (M / M) =8. 7) using 15 background quasars (median impact parameter, D = 140 pkpc), as part of the MUSE Quasar-fields Blind Emitters Survey (MUSEQuBES). We find that the H i column density (N (H\, I) ) profile around isolated star-forming galaxies spanning ≈3 dex in M⋆ is well described by a power law with slope ≈−3 when expressed as a function of normalized impact parameter D/Rvir. The H i covering fraction (κ) within the virial radius for log₁₀ (N (H\, I) / cm^-2) =14 is significantly lower in high-mass passive galaxies than in isolated star-forming galaxies. The κ-profile of isolated star-forming galaxies suggests a characteristic size of the H i-rich CGM of ≈1. 5Rvir across the stellar mass range. The mean H i mass in the outer CGM (0. 3–1 Rvir) increases with M⋆, ranging from ≈105. 0 to 106. 6 M. The b-parameters of the strongest H i components correlate and anti-correlate with specific star-formation rate (sSFR) and mass, respectively, with 2σ significance. Broad Lyα absorbers (BLAs) with b 60 km~s^-1 are predominantly associated with high-mass galaxies, likely tracing the warm-hot phase of the CGM. The velocity centroids of H i components indicate that absorbers at D Rvir are largely consistent with being gravitationally bound to their galaxies, independent of stellar mass. Finally, leveraging ≈3000 galaxies from the wide-field Magellan follow-up of six MUSEQuBES fields, we find that non-isolated galaxies exhibit an H i-rich environment extending roughly three times farther than in isolated counterparts.