The spectral energy distribution of the redshift 7.1 quasar ULAS
  J1120+0641
  We present new observations of the highest-redshift quasar known, ULAS
J1120+0641, redshift $z=7.084$, obtained in the optical, at near-, mid-, and
far-infrared wavelengths, and in the sub-mm. We combine these results with
published X-ray and radio observations to create the multiwavelength spectral
energy distribution (SED), with the goals of measuring the bolometric
luminosity $L_{\rm bol}$, and quantifying the respective contributions from the
AGN and star formation. We find three components are needed to fit the data
over the wavelength range $0.12-1000\,\mu$m: the unobscured quasar accretion
disk and broad-line region, a dusty clumpy AGN torus, and a cool 47K modified
black body to characterise star formation. Despite the low signal-to-noise
ratio of the new long-wavelength data, the normalisation of any dusty torus
model is constrained within $\pm40\%$. We measure a bolometric luminosity
$L_{\rm bol}=2.6\pm0.6\times10^{47}\,$erg$\,$s$^{-1}=6.7 \pm
1.6\times10^{13}L_{\odot}$, to which the three components contribute
$31\%,32\%,3\%$, respectively, with the remainder provided by the extreme UV
$<0.12\,\mu$m. We tabulate the best-fit model SED. We use local scaling
relations to estimate a star formation rate (SFR) in the range $60-270\,{\rm
M}_\odot$/yr from the [C$\,{\scriptsize \rm II}$] line luminosity and the
$158\,\mu$m continuum luminosity. An analysis of the equivalent widths of the
[C$\,{\scriptsize \rm II}$] line in a sample of $z>5.7$ quasars suggests that
these indicators are promising tools for estimating the SFR in high-redshift
quasars in general. At the time observed the black hole was growing in mass
more than 100 times faster than the stellar bulge, relative to the mass ratio
measured in the local universe, i.e. compared to ${M_{\rm BH}}/{M_{\rm bulge}}
\simeq 1.4\times10^{-3}$, for ULAS J1120+0641 we measure ${\dot{M}_{\rm
BH}}/{\dot{M}_{\rm bulge}} \simeq 0.2$.
