Detection of Metal-Rich, Cool-Warm Gas in the Outskirts of Galaxy
  Clusters
  We present an ultraviolet quasar absorption line analysis of metal lines
associated with three strong intervening H I absorbers (with $N$(H I) $>$
10$^{16.5}$ cm$^{-2}$) detected in the outskirts of Sunyaev-Zel'dovich (SZ)
effect-selected galaxy clusters ($z_{\rm cl} \sim 0.4 - 0.5$), within
clustocentric impact parameters of $\rho_{cl}$ $\sim$ $(1.6 - 4.7)r_{500}$.
Discovered in a recent set of targeted far-UV $HST$/COS spectroscopic
observations, these absorbers have the highest H I column densities ever
observed in the outskirts of galaxy clusters, and are also rich in metal
absorption lines. Photoionization models yield single phase solutions for the
three absorbers with gas densities of $n_{H} \sim 10^{-3} - 10^{-4}$ cm$^{-3}$
and metallicities of [X/H] $>$ -1.0 (from one-tenth solar to near-solar). The
widths of detected absorption lines suggest gas temperatures of $T \sim 10^4$
K. The inferred densities (temperatures) are significantly higher (lower)
compared to the X-ray emitting intracluster medium in cluster cores. The
absorbers are tracing a cool phase of the intracluster gas in the cluster
outskirts, either associated with gas stripped from cluster galaxies via
outflows, tidal streams or ram-pressure forces, or denser regions within the
intracluster medium that were uniformly chemically enriched from an earlier
epoch of enhanced supernova and AGN feedback.
