We present the first observation of a galaxy ( z = 0.2 ) that exhibits metal-line absorption back-illuminated by the galaxy ( “ down-the-barrel ” ) and transversely by a background quasar at a projected distance of 58 kpc .
Both absorption systems , traced by Mg ii , are blueshifted relative to the galaxy systemic velocity .
The quasar sight-line , which resides almost directly along the projected minor axis of the galaxy , probes Mg i and Mg ii absorption obtained from Keck/LRIS and Ly \alpha , Si ii and Si iii absorption obtained from HST /COS .
For the first time , we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption .
We find that the modeled down-the-barrel deprojected outflow velocities range between V _ { dtb } = 45 - 255 km s ^ { -1 } .
The transverse bi-conical outflow model , assuming constant-velocity flows perpendicular to the disk , requires wind velocities V _ { outflow } = 40 - 80 km s ^ { -1 } to reproduce the transverse Mg ii absorption kinematics , which is consistent with the range of V _ { dtb } .
The galaxy has a metallicity , derived from H \alpha and N ii , of [ O/H ] = -0.21 \pm 0.08 , whereas the transverse absorption has [ { X / H } ] = -1.12 \pm 0.02 .
The galaxy star-formation rate is constrained between 4.6–15 M _ { \odot } yr ^ { -1 } while the estimated outflow rate ranges between 1.6–4.2 M _ { \odot } yr ^ { -1 } and yields a wind loading factor ranging between 0.1 - 0.9 .
The galaxy and gas metallicities , the galaxy–quasar sight-line geometry , and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy .
The \sim 1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc .