2012ApJ...751L..25V

Using the IRAM Plateau de Bure Interferometer, we report the detection of the 158 µm [C II] emission line and underlying dust continuum in the host galaxy of the quasar ULAS J112001.48+064124.3 (hereafter J1120+0641) at z = 7.0842±0.0004. This is the highest redshift detection of the [C II] line to date, and allows us to put the first constraints on the physical properties of the host galaxy of J1120+0641. The [C II] line luminosity is 1.2±0.2x10⁹ L_☉, which is a factor ∼4 lower than observed in a luminous quasar at z = 6.42 (SDSS J1148+5251). The underlying far-infrared (FIR) continuum has a flux density of 0.61±0.16 mJy, similar to the average flux density of z ∼ 6 quasars that were not individually detected in the rest-frame FIR. Assuming that the FIR luminosity of L_FIR= 5.8x10¹¹-1.8 x10¹² L_☉ is mainly powered by star formation, we derive a star formation rate in the range 160-440 M_☉/yr and a total dust mass in the host galaxy of 6.7x10⁷-5.7x10⁸ M_☉(both numbers have significant uncertainties given the unknown nature of dust at these redshifts). The [C II] line width of σ_V= 100±15 km/s is among the smallest observed when compared to the molecular line widths detected in z ∼ 6 quasars. Both the [C II] and dust continuum emission are spatially unresolved at the current angular resolution of 2.0x1.7 arcsec² (corresponding to 10x9 kpc² at the redshift of J1120+0641).