We report detections of six high-redshift ( 1.8 \leq z \leq 6.4 ) , optically luminous , radio-quiet quasars at 350 µm , using the SHARC II bolometer camera at the Caltech Submillimeter Observatory .
Our observations double the number of high-redshift quasars for which 350 µm photometry is available .
By combining the 350 µm measurements with observations at other submillimeter/millimeter wavelengths , for each source we have determined the temperature of the emitting dust ( ranging from 40 to 60 \mathrm { K } ) and the far-infrared luminosity ( 0.6 to 2.2 \times 10 ^ { 13 } \mathrm { L _ { \odot } } ) .
The combined mean spectral energy distribution ( SED ) of all high-redshift quasars with two or more rest frame far-infrared photometric measurements is best fit with a greybody with temperature of 47 \pm 3 \mathrm { K } and a dust emissivity power-law spectral index of \beta = 1.6 \pm 0.1 .
This warm dust component is a good tracer of the starburst activity of the quasar host galaxy .
The ratio of the far-infrared to radio luminosities of infrared luminous , radio-quiet high-redshift quasars is consistent with that found for local star-forming galaxies .