MUSEQuBES: Probing Anisotropies in Gas and Metal Distributions in the Circumgalactic Medium

Abstract We investigate the azimuthal dependence of H i and O vi -bearing gas in the circumgalactic medium (CGM) of 113 isolated galaxies in the redshift range 0.12 < z < 0.75, including 91 new measurements from the MUSE Quasar-fields Blind Emitters Survey (MUSEQuBES). Of these, measurements for 46 galaxies lie within the virial radius ( R vir ), including 36 non-face-on systems for which azimuthal angle ( ϕ ) measurements are robust. The H i covering fraction ( κ H I ) within R vir of low-mass (7 < log 10 ( M ⋆ / M ⊙ ) ≤ 9) galaxies, for a threshold column density of log 10 ( N ( H I ) / cm − 2 ) = 14.5 , exhibits an enhancement along both the disk plane ( ϕ ≲ 20°) and in the polar direction ( ϕ ≳ 70°). In contrast, such a bimodal distribution is not observed for higher mass galaxies (9 < log 10 ( M ⋆ / M ⊙ ) ≤ 11.3). Similarly, the O vi covering fraction ( κ O VI ), for a threshold of log 10 ( N ( O VI ) / cm − 2 ) = 14.0 , shows a tentative enhancement along both the projected major and minor axes for low-mass galaxies. In contrast, O vi -bearing gas around higher-mass galaxies appears more uniformly distributed, with no significant azimuthal dependence. Finally, using the halo circular-velocity-normalized pixel-velocity two-point correlation function (TPCF), we find that O vi absorbers are kinematically narrower along the disk plane compared to the polar directions of the host galaxies with similar stellar mass distributions. The observed isotropic distribution of O vi in high-mass halos suggests that its spatial distribution is governed by global halo properties; however, the O vi kinematics retain memory of the site of origin.