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

We present a detailed analysis of a large-scale galactic outflow in the circumgalactic medium of a massive (M-h similar to 10(12.5) M-circle dot), star-forming (similar to 6.9 M-circle dot yr(-1)), sub-L-* (similar to 0.5L(B)*) 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 (i = 63 degrees) and the azimuthal angle (Phi = 73 degrees) 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 O VI (log N= 15.16 +/- 0.04, Delta v(90) = 419 km s(-1)) and N V (log N= 14.69 +/- 0.07, Delta v(90) = 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 (similar to 10(-4.2) cm(-3)), diffuse (similar to 10 kpc), cool (similar to 10(4) K) photoionized gas with a super-solar metallicity ([X H] greater than or similar to 0.3). From the observed narrowness of the Ly beta profile, the non-detection of S IV absorption, and the presence of strong C IV 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 similar to 10(-2.5) cm(-3) and a metallicity of [X H] greater than or similar to -1.4 is possibly tracing recycled halo gas. We estimate an outflow mass of similar to 2 x 10(10) M., a mass-flow rate of similar to 54 M-circle dot yr(-1), a kinetic luminosity of similar to 9 x 10(41) erg s(-1), and a mass loading factor of similar to 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.