An ALMA [CII] survey of 27 quasars at z>5.94
  We present a survey of the [CII] 158 $\mu$m line and underlying far-infrared
(FIR) dust continuum emission in a sample of 27 z>6 quasars using the Atacama
Large Millimeter Array (ALMA) at ~1" resolution. The [CII] line was
significantly detected (at >5-sigma) in 23 sources (85%). We find typical line
luminosities of $L_{\rm [CII]}=10^{9-10}$ L$_\odot$, and an average line width
of ~385 km/s. The [CII]-to-far-infrared luminosity ratio ([CII]/FIR) in our
sources span one order of magnitude, highlighting a variety of conditions in
the star-forming medium. Four quasar host galaxies are clearly resolved in
their [CII] emission on a few kpc scales. Basic estimates of the dynamical
masses of the host galaxies give masses between $2\times10^{10}$ and
$2\times10^{11}$ M$_\odot$, i.e., more than an order of magnitude below what is
expected from local scaling relations, given the available limits on the masses
of the central black holes ($>3\times10^8$ M$_\odot$, assuming
Eddington-limited accretion). In stacked ALMA [CII] spectra of individual
sources in our sample, we find no evidence of a deviation from a single
Gaussian profile. The quasar luminosity does not strongly correlate with either
the [CII] luminosity or equivalent width. This survey (with typical on-source
integration times of 8 min) showcases the unparalleled sensitivity of ALMA at
millimeter wavelengths, and offers a unique reference sample for the study of
the first massive galaxies in the universe.
