2015ApJ...801..126R

Emission from metal resonant lines has recently emerged as a potentially powerful probe of the structure of galactic winds at low and high redshift. In this work, we present only the second example of spatially resolved observations of Na i D emission from a galactic wind in a nearby galaxy (and the first 3D observations at any redshift). F05189-2524, a nearby (z = 0.0428) ultraluminous infrared galaxy powered by a quasar, was observed with the integral field unit on the Gemini Multi-Object Spectrograph at Gemini South. Na i D absorption in the system traces dusty filaments on the near side of an extended, active galactic nucleus-driven galactic wind (with projected velocities up to 2000 km/s). These filaments (A_v ≲(c)4 and N(H) ≲ 10²²/cm2) simultaneously obscure the stellar continuum and Na i D emission lines. The Na i D emission lines serve as a complementary probe of the wind: they are strongest in regions of low foreground obscuration and extend up to the limits of the field of view (galactocentric radii of 3 kpc). An azimuthally symmetric Sérsic model extincted by the same foreground screen as the stellar continuum reproduces the Na i D emission line surface brightness distribution except in the inner regions of the wind, where some emission-line filling of absorption lines may occur. The presence of detectable Na i D emission in F05189-2524 may be due to its high continuum surface brightness at the rest wavelength of Na i D. These data uniquely constrain current models of cool gas in galactic winds and serve as a benchmark for future observations and models.