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

摘要

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 ~(-1) , with respect to the systemic peak emission, and a luminosity of L ′ = 9.9 × 10~(9) μ ~(-1) K km s ~(-1) pc ~(-2) , 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 ? = 3?7.4 × 10~(3) M _(⊙) /yr and momentum boost ? _(OF)/ ? _(AGN) ~ 2?6 , which is therefore consistent with a momentum conserving flow. For the largest ? _(OF) 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 = ? _(OF)/ 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_(2)H~(+) (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.