350 Micron Dust Emission from High-Redshift Objects

Abstract

We report observations of a sample of high-redshift sources (1.8 z 4.7), mainly radio-quiet quasars, at 350 μm using the bolometer camera SHARC (Submillimeter High Angular Resolution Camera) at the Caltech Submillimeter Observatory. Nine sources were detected (4 σ), and upper limits were obtained for 11 with 350 μm flux density limits (3 σ) in the range 30-125 mJy. Combining published results at other far-infrared and millimeter wavelengths with the present data, we are able to estimate the temperature of the dust, finding relatively low values, averaging 50 K. From the spectral energy distribution, we derive dust masses of a few times 10⁸ h M_☉ and luminosities of (4-33) × 10¹² h L_☉ (uncorrected for any magnification), which imply substantial star formation activity. Thus, both the temperature and dust masses are not very different from those of local ultraluminous infrared galaxies. For this redshift range, the 350 μm observations trace the 60-100 μm rest-frame emission and are thus directly comparable with IRAS studies of low-redshift galaxies.