CO (7−6), [C i] 370 μm, and [N ii] 205 μm Line Emission of the QSO BRI 1335-0417 at Redshift 4.407

Abstract

We present the results from our Atacama Large Millimeter/submillimeter Array (ALMA) imaging observations of the CO(7−6), [C i ] 370 μ m (hereafter [C i ]), and [N ii ] 205 μ m (hereafter [N ii ]) lines and their underlying continuum emission of BRI 1335-0417, an infrared bright quasar at z  = 4.407. At the achieved resolutions of ∼1.″1 to 1.″2 (or 7.5–8.2 kpc), the continuum at 205 and 372 μ m (rest frame), the CO(7−6), and the [C i ] emissions are at best barely resolved whereas the [N ii ] emission is well resolved with a beam-deconvolved major axis of 1.″3(±0.″3) or 9(±2) kpc. As a warm dense gas tracer, the CO(7−6) emission shows a more compact spatial distribution and a significantly higher peak velocity dispersion than the other two lines that probe lower density gas, a picture favoring a merger-triggered star formation (SF) scenario over an orderly rotating SF disk. The CO(7−6) data also indicate a possible QSO-driven gas outflow that reaches a maximum line-of-sight velocity of 500–600 km s −1 . The far-infrared (FIR) dust temperature ( T dust ) of 41.5 K from a graybody fit to the continuum agrees well with the average T dust inferred from various line luminosity ratios. The resulting L CO(7–6) / L FIR luminosity ratio is consistent with that of local luminous infrared galaxies powered predominantly by SF. The L CO(7–6) -inferred SF rate is 5.1(±1.5) × 10 3 M ⊙ yr −1 . The system has an effective star-forming region of kpc in diameter and a molecular gas reservoir of ∼5 × 10 11 M ⊙ .