350 μm Dust Emission from High‐Redshift Quasars

We report detections of six high-redshift (1.8 < z < 6.4), opticallyluminous, radio-quiet quasars at 350 micron, using the SHARC II bolometercamera at the Caltech Submillimeter Observatory. Our observations double thenumber of high-redshift quasars for which 350 micron photometry is available.By combining the 350 micron measurements with observations at othersubmillimeter/millimeter wavelengths, for each source we have determined thetemperature of the emitting dust (ranging from 40 to 60 K) and the far-infraredluminosity (0.6 to 2.2 x 10(13) Lo). The combined mean spectral energydistribution (SED) of all high-redshift quasars with two or more rest framefar-infrared photometric measurements is best fit with a greybody withtemperature of 47 +- 3 K and a dust emissivity power-law spectral index of beta= 1.6 +- 0.1. This warm dust component is a good tracer of the starburstactivity of the quasar host galaxy. The ratio of the far-infrared to radioluminosities of infrared luminous, radio-quiet high-redshift quasars isconsistent with that found for local star-forming galaxies.Comment: 12 pages, 6 figures, accepted for publication in Ap