Kinematic analysis of an Ultra-Strong MgII absorber at z~1.13 linking to Circumgalactic Gas Structures

We present a spectroscopic and imaging analysis of the zgal ≈ 1.1334 ultra-strong MgII absorption system identified in the $VLT$/UVES spectrum of a background quasar located at ρ≈ 18 kpc from a star-forming galaxy. Low ionization metal lines like MgI, FeII, and CaII are also detected for this absorber. The HI lines are outside of the wavelength coverage. The MgII has a rest-frame equivalent width of Wᵣ(2796) =3.185 +/- 0.032 A∘, with the absorption spread across Δv ≈ 460 km~s⁻¹ in several components. A component-by-component ionization modeling shows several of these components having solar and higher metallicities. The models also predict a total HI column density of log[N(HI)/cm⁻²] ≈ 22.5, consistent with ultra-strong MgII absorbers being sub-Damped Lyman Alpha and Damped Lyman Alpha systems. The absorber is well within the virial radius of the nearest galaxy which has a stellar mass M_* = 4.7 × 10¹⁰~M_, and a star formation rate of ≈ 8.3~M_~yr⁻¹. The absorption is along the projected major axis of the galaxy with a velocity spread that is wider than the galaxy's disk rotation. From the kinematic analysis of the absorber and the galaxy, the origin of the absorption can be attributed to a combination of circumgalactic gas structures, some corotating with the disk and the rest at line-of-sight velocities outside of the disk rotation.