Detection of low-metallicity warm plasma in a galaxy overdensity environment at z ̃ 0.2

摘要: We present results from the analysis of a multiphase O VI - broad Ly-alpha absorber at z = 0.19236 in HST/COS spectrum PG 1121+422. The low and intermediate ionization metal lines this have single narrow component, whereas has possible component with b(HI) $\sim 71$ km/s. Ionization models favor ions coming $T \sim 8,500$ K, moderately dense photoionized gas near solar metallicities. weak requires separate phase that is collisionally ionized. coupled BLA suggests 3.2 \times 10^5$ significantly lower abundance 1.8$ orders magnitude higher total hydrogen column density compared to phase. SDSS shows 12 luminous ($> L^*$) galaxies $\rho \leq 5$ Mpc, $|\Delta v| 800$ km/s region surrounding absorber, outside virial bounds nearest galaxy. warm consistent being transition temperature plasma either interface regions between hot intragroup cooler clouds within group, or associated high velocity halo $\lesssim L^*$ highlights advantage VI-BLA absorbers as model independent probes baryon reserves.