Keck High-Resolution Spectroscopy of Outflows in Infrared-luminous Galaxies

Several recent studies have determined that large quantities of neutral gasare outflowing from the nuclei of almost all infrared-luminous galaxies. Thesemeasurements show that winds in infrared-luminous galaxies play a significantrole in the evolution of galaxies and the intergalactic medium at redshifts z >1, when infrared-luminous galaxies dominated the star formation rate of theuniverse. These conclusions rely on moderate resolution spectra (FWHM > 65km/s) of the NaI D absorption line and the assumption that there are nounresolved, saturated velocity components. For the first time, we present highresolution spectra (FWHM = 13 km/s) of massive, infrared-luminous galaxies. Thefive galaxies in our sample are known to host outflows on the basis of previousobservations. With the present observations, all NaI D velocity components areresolved with tau(NaI D1 5896 A) < 6. The column densities we measure areconsistent within the errors with those measured from moderate-resolutionobservations. This confirms that the mass, momentum, and energy of outflowinggas in infrared-luminous galaxies have been measured correctly by previousstudies.Comment: 1 figure; to be published in 2005 Sep 20 issue of ApJ