2016ApJ...816...37V

We present ALMA detections of the [C ii] 158 µm emission line and the underlying far-infrared (FIR) continuum of three quasars at 6.6 < z < 6.9 selected from the VIKING survey. The [C ii] line fluxes range between 1.6 and 3.4 Jy km/s ([C ii] luminosities ~(1.9-3.9)x10⁹ L_☉). We measure continuum flux densities of 0.56-3.29 mJy around 158 µm (rest frame), with implied FIR luminosities of (0.6-7.5)x10¹² L_☉ and dust masses M_d= (0.7-24)x10⁸ M_☉. In one quasar we derive a dust temperature of 30_–9⁺¹² K from the continuum slope, below the canonical value of 47 K. Assuming that the [C ii] and continuum emission are powered by star formation, we find star formation rates from 100 to 1600 M_☉/yr based on local scaling relations. The L_[C ii]_/LFIR_ratios in the quasar hosts span a wide range from (0.3-4.6)x10^–3, including one quasar with a ratio that is consistent with local star-forming galaxies. We find that the strength of the L_[C ii]_ and 158 µm continuum emission in z ≳ 6 quasar hosts correlates with the quasar's bolometric luminosity. In one quasar, the [C ii] line is significantly redshifted by ∼1700 km/s with respect to the Mg ii broad emission line. Comparing to values in the literature, we find that, on average, the Mg ii is blueshifted by 480 km/s (with a standard deviation of 630 km/s) with respect to the host galaxy redshift, i.e., one of our quasars is an extreme outlier. Through modeling we can rule out a flat rotation curve for our brightest [C ii] emitter. Finally, we find that the ratio of black hole mass to host galaxy (dynamical) mass is higher by a factor of 3-4 (with significant scatter) than local relations.