Discovery of extremely low-metallicity circumgalactic gas at $z=0.5$ toward Q0454-220

Jackson M. Norris, Sowgat Muzahid, Jane C. Charlton +3

We have obtained new observations of the absorption system at $z_{\mathrm{abs}}=0.48$ toward QSO Q0454-220, which we use to constrain its chemical and physical conditions. The system…