AN EXTREME METALLICITY, LARGE-SCALE OUTFLOW FROM A STAR-FORMING GALAXY ATz∼ 0.4

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Abstract
We present a detailed analysis of a large-scale galactic outflow in the circumgalactic medium of a massive (), star-forming ( yr?1), sub-L* () galaxy at z = 0.39853 that exhibits a wealth of metal-line absorption in the spectra of the background quasar Q 0122?003 at an impact parameter of 163 kpc. The galaxy inclination angle () and the azimuthal angle () imply that the QSO sightline is passing through the projected minor-axis of the galaxy. The absorption system shows a multiphase, multicomponent structure with ultra-strong, wide velocity spread ( 419 km s?1) and ( 285 km s?1) lines that are extremely rare in the literature. The highly ionized absorption components are well explained as arising in a low density ( cm?3), diffuse (~10 kpc), cool (~104 K) photoionized gas with a super-solar metallicity (). From the observed narrowness of the Ly? profile, the non-detection of absorption, and the presence of strong absorption in the low-resolution FOS spectrum, we rule out equilibrium/non-equilibrium collisional ionization models. The low-ionization photoionized gas with a density of cm?3 and a metallicity of is possibly tracing recycled halo gas. We estimate an outflow mass of a mass-flow rate of a kinetic luminosity of erg s?1, and a mass loading factor of ~8 for the outflowing high-ionization gas. These are consistent with the properties of "down-the-barrel" outflows from infrared-luminous starbursts as studied by Rupke et al. Such powerful, large-scale, metal-rich outflows are the primary means of sufficient mechanical and chemical feedback as invoked in theoretical models of galaxy formation and evolution.

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