Far-Infrared Properties of the Bright, Gravitationally Lensed Quasar
  J0439+1634 at z=6.5
  We present IRAM/NOEMA, JCMT/SCUBA-2 and VLA observations of the most distant
known gravitationally lensed quasar J0439+1634 at z = 6.5. We detect strong
dust emission, [CII] 158 $\mu$m, [CI] 369 $\mu$m, [OI] 146 $\mu$m, CO(6-5),
CO(7-6), CO(9-8), CO(10-9), H$_{\rm 2}$O $3_{\rm 1,2}-2_{\rm 2,1}$, and H$_{\rm
2}$O $3_{\rm 2,1}-3_{\rm 1,2}$ lines as well as a weak radio continuum. The
strong [CII] line yields a systemic redshift of the host galaxy to be
z=6.5188$\pm$0.0001. The magnification makes J0439+1634 the far-infrared (FIR)
brightest quasar at z > 6 known, with the brightest [CII] line yet detected at
this redshift. The FIR luminosity is (3.4$\pm$0.2)$\times$10$^{13}$ $\mu^{-1}$
$L_{\odot}$, where $\mu$ $\sim$ 2.6 - 6.6 is the magnification of the host
galaxy, estimated based on the lensing configuration from HST imaging. We
estimate the dust mass to be (2.2$\pm$0.1)$\times$10$^{9}$ $\mu^{-1}$
$M_{\odot}$. The CO Spectral Line Energy Distribution using four CO lines is
best fit by a two-component model of the molecular gas excitation. The
estimates of molecular gas mass derived from CO lines and atomic carbon mass
are consistent, in the range of 3.9 - 8.9 $\times$10$^{10} \mu^{-1}$
$M_{\odot}$. The [CII]/[CI], [CII]/CO, and [OI]/[CII] line luminosity ratios
suggest a photodissociation region model with more than one component. The
ratio of H$_{\rm 2}$O $3_{\rm 2,1}-3_{\rm 1,2}$ line luminosity to $L_{\rm
TIR}$ is consistent with values in local and high redshift
ultra-/hyper-luminous infrared galaxies. The VLA observations reveal an
unresolved radio continuum source, and indicate that J0439+1634 is a radio
quiet quasar with R = 0.05 - 0.17.
