We analyze the absorption and emission-line profiles produced by a set of simple, cool gas wind models motivated by galactic-scale outflow observations. We implement monte carlo radiative transfer techniques that track the propagation of scattered an
d fluorescent photons to generate 1D spectra and 2D spectral images. We focus on the MgII 2796,28303 doublet and FeII UV1 multiplet at ~2600A, but the results are applicable to other transitions that trace outflows (e.g. NaI, Lya, SiII). By design, the resonance transitions show blue-shifted absorption but one also predicts strong resonance and fine-structure line-emission at roughly the systemic velocity. This line-emission `fills-in the absorption reducing the equivalent width by up to 50%, shift the absorption-lin centroid by tens of km/s, and reduce the effective opacity near systemic. Analysis of cool gas outflows that ignores this line-emission may incorrectly infer that the gas is partially covered, measure asignificantly lower peak optical depth, and/or conclude that gas at systemic velocity is absent. Because the FeII lines are connected by optically-thin transitions to fine-structure levels, their profiles more closely reproduce the intrinsic opacity of the wind. Together these results naturally explain the absorption and emission-line characteristics observed for star-forming galaxies at z<1. We also study a scenario promoted to describe the outflows of z~3 Lyman break galaxies and find prfiles inconsistent with the observations due to scattered photon emission. Although line-emission complicates the analysis of absorption-line profiles, the surface brightness profiles offer a unique means of assessing the morphology and size of galactic-scale winds. Furthermore, the kinematics and line-ratios offer powerful diagnostics of outflows, motivating deep, spatially-extended spectroscopic observations.
