Resolved [CII] Emission from z>6 Quasar Host -- Companion Galaxy Pairs
  We report on ~0.35"(~2 kpc) resolution observations of the [CII] and dust
continuum emission from five z>6 quasar host-companion galaxy pairs obtained
with the Atacama Large Millimeter/submillimeter Array. The [CII] emission is
resolved in all galaxies, with physical extents of 3.2-5.4 kpc. The dust
continuum is on-average 40% more compact, which results in larger [CII]
deficits in the center of the galaxies. However, the measured [CII] deficits
are fully consistent with those found at lower redshifts. Four of the galaxies
show [CII] velocity fields that are consistent with ordered rotation, while the
remaining six galaxies show no clear velocity gradient. All galaxies have high
(~80-200 km/s) velocity dispersions, consistent with the interpretation that
the interstellar medium (ISM) of these high redshift galaxies is turbulent. By
fitting the galaxies with kinematic models, we estimate the dynamical mass of
these systems, which range between (0.3 -> 5.4) x 1E10 Msun. For the three
closest separation galaxy pairs, we observe dust and [CII] emission from gas in
between and surrounding the galaxies, which is an indication that tidal
interactions are disturbing the gas in these systems. Although gas exchange in
these tidal interactions could power luminous quasars, the existence of quasars
in host galaxies without nearby companions suggests that tidal interactions are
not the only viable method for fueling their active centers. These observations
corroborate the assertion that accreting supermassive black holes do not
substantially contribute to the [CII] and dust continuum emission of the quasar
host galaxies, and showcase the diverse ISM properties of galaxies when the
universe was less than one billion years old.
