Low-metallicity gas clouds in a galaxy protocluster at redshift 2.38

We present high- resolution spectroscopy of a QSO whose sight line passes through the halo of a pair of elliptical galaxies at redshift 2.38. This pair of galaxies probably lies at the center of a galaxy protocluster and is embedded in a luminous extended Lyalpha nebula. The QSO sight line intersects two small gas clouds within this halo. These clouds have properties similar to those of high- velocity clouds seen in the halo of the Milky Way. The gas is in a cool (< 2 x 10(4) K) and at least 20% neutral phase, with metallicities in the range - 3.0 < [ Fe/ H] < - 1.1 neutral hydrogen column densities of ∼ 10(19.5) cm(-2). The origin of these clouds is unclear. The presence of low-metallicity gas within this possible protocluster implies either that the intracluster medium has not been enriched with metals at this redshift, or the clouds are embedded within a hot, ionized, metal- rich gas phase.