Outflowing atomic and molecular gas at z ∼ 0 . 67 towards 1504 + 377

We report the detection of OH 1667 MHz and wide HI 21cm absorption at z ∼ 0.67 towards the red quasar 1504+377, with the Green Bank Telescope and the Giant Metrewave Radio Telescope. The HI 21cm absorption extends over a velocity range of ∼ 600 km/s blueward of the quasar redshift (z = 0.674), with the new OH 1667 MHz absorption component at ∼ −430 km s−1, nearly coincident with earlier detections of mm-wave absorption at z ∼ 0.6715. The atomic and molecular absorption appear to arise from a fast gas outflow from the quasar, with a mass outflow rate Ṁ ∼ 12M⊙ yr−1 and a molecular hydrogen fraction fH2 ≡ (NH2/NHI) ∼ 0.2. The radio structure of 1504+377 is consistent with the outflow arising due to a jet-cloud interaction, followed by rapid cooling of the cloud material. The observed ratio of HCO to OH column densities is ∼ 20 times higher than typical values in Galactic and high-z absorbers. This could arise due to small-scale structure in the outflowing gas on sub-parsec scales, which would also explain the observed variability in the HI 21cm line.