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Galactic-scale outflows driven by starbursts and/or active galactic nuclei (AGN) are key ingredients to theoretical models and numerical simulations of galaxy assembly and evolution. The feedback induced by the presence of these outflows (or winds) may affect the evolution and formation of a galaxy by regulating the amount of cold, dense gas responsible for star formation and black hole accretion.

We present the results from a systematic search for galactic-scale, molecular (OH 119 μm) outflows in a sample of 52 Local Volume (d < 50 Mpc) Burst Alert Telescope detected active galactic nuclei (BAT AGN) with Herschel-PACS. We combine the results from our analysis of the BAT AGN with the published Herschel/PACS data of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. Our data show that both the starburst and AGN contribute to driving OH outflows, but the fastest OH winds require AGN with quasar-like luminosities.

We also analyze Spitzer InfraRed Spectrograph (IRS) observations of the OH 35 μm feature in 15 nearby (z < 0.06) (ultra-)luminous infrared galaxies (U/LIRGs). The measured OH 35 μm equivalent widths are used to compute an average OH column density which is then compared to the hydrogen column density for a typical optical depth at 35 μm of ∼0.5 and gas-to-dust ratio of 125 to derive an OH−to−H abundance ratio of X_{OH} = 1.01 ± 0.15 × 10^{−6}. The OH 35 μm line profiles predicted from published radiative transfer models constrained by observa- tions of OH 65, 79, 84, and 119 μm in five objects are found to be consistent with the IRS OH 35 μm spectra.

Finally, we analyze Herschel-PACS observations of five atomic fine-structure transition lines ([O I] 63 μm, [O III] 88 μm, [N II] 122 μm, [O I] 145 μm, and [C II] 158 μm) in seven nearby (d < 16 Mpc) galaxies with well-known galactic- scale outflows (Cen A, Circinus, M 82, NGC 253, NGC 1068, NGC 3079, and NGC 4945). With this suite of atomic emission lines, we investigate the cool neutral atomic (T ~ 10^3 K) and warm ionized (T ~ 10^4 K) gas phases within each outflow. The outflows in the Herschel data are spatially isolated from the galactic disk based on the kinematic signatures of the outflows. The spatial distribution and physical properties of the outflows detected in the Herschel data are compared with published results at other wavelengths. For completeness, an analysis of the molecular gas traced by OH 119 μm is also presented.