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-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 +/- 40%. We measure a bolometric luminosity L-bol = 2.6 +/- 0.6 x 10(47) erg s(-1) = 6.7 +/- 1.6 x 10(13) L-circle dot, 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 M-circle dot/yr from the [C II] line luminosity and the 158 mu m continuum luminosity. An analysis of the equivalent widths of the [C 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-BH/M-bulge similar or equal to 1.4 x 10(-3), for ULAS J1120+0641 we measure. (M)(BH) over dot = (M)(bulge) over dot similar or equal to 0.2.