Where Do CIV Absorbers Live?

This video briefly summarizes Hasan et al. (2022) [1], a follow-up paper to our observational survey of CIV absorption lines in high-resolution quasar spectra (Hasan et al. 2020 [2]). By combining absorber statistics with observed galaxy statistics, we infer the spatial extent of CIV-absorbing gas relative to galaxies. We find that if each absorber is associated with a single galaxy halo, weak CIV absorbers (${\rm EW} \ge 0.05 \, {\rm \AA}$) typically extend out to the outer circumgalactic medium (CGM) or the intergalactic medium (IGM), while stronger absorbers with higher EW typically live deeper in the CGM, implying different origin mechanisms for optically thick and optically thin absorbers. Available observational data suggests that massive galaxies ($\sim L^*$) have more extended metal-enriched gas envelopes than dwarf galaxies ($\sim 0.1 \, L^*$), and that this is likely an effect of the nearby environment of massive galaxies including surrounding satellites, especially at early epochs. Our model of the spatial extent of gas will benefit greatly from a significant increase in multi-object/integral field spectroscopic observations and JWST observations of early galactic outflows.