On the discovery of fast molecular gas in the UFO/BAL quasar APM 08279+5255 at z = 3.912

Abstract

We have performed a high sensitivity observation of the UFO/BAL quasar APM 08279+5255 at z = 3.912 with NOEMA at 3.2 mm, aimed at detecting fast moving molecular gas. We report the detection of blueshifted CO(4-3) with maximum velocity (v95%) of -1340 km s<SUP>-1</SUP>, with respect to the systemic peak emission, and a luminosity of L' = 9.9 × 10<SUP>9</SUP>μ<SUP>-1</SUP> K km s<SUP>-1</SUP> pc<SUP>-2</SUP>, where μ is the lensing magnification factor. We discuss various scenarios for the nature of this emission and conclude that this is the first detection of fast molecular gas at redshift > 3. We derived a mass flow rate of molecular gas in the range Ṁ = 3-7.4 × 10<SUP>3</SUP>M<SUB>☉</SUB>/yr and momentum boost Ṗ<SUB>OF</SUB>/Ṗ<SUB>AGN</SUB> 2-6, which is therefore consistent with a momentum conserving flow. For the largest Ṗ<SUB>OF</SUB> the scaling is also consistent with an energy conserving flow with an efficiency of 10-20%. The present data can hardly discriminate between the two expansion modes. The mass loading factor of the molecular outflow η = Ṁ<SUB>OF</SUB>/SFR is ≫ 1. We also detected a molecular emission line at a frequency of 94.83 GHz corresponding to a rest-frame frequency of 465.8 GHz; we tentatively identified this frequency with the cation molecule N<SUB>2</SUB>H<SUP>+</SUP>(5-4), which would be the first detection of this species at high redshift. We discuss the alternative possibility that this emission is due to a CO emission line from the, so far undetected, lens galaxy. Further observations of additional transitions of the same species with NOEMA can discriminate between the two scenarios. <P />This work is based on observations carried out under project numbers S15CW and E15AF with the IRAM NOEMA Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). The reduced spectrum (FITS file) is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A30">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A30