Submillimeter spectrum and dust mass of the primeval galaxy IRAS 10214 + 4724

Abstract

We measured with the IRAM 30 m telescope the continuum flux of the extremely luminous primeval galaxy IRAS 10214+4724 at a wavelength of 1.2 mm. This is the longest wavelength at which this galaxy's thermal continuum radiation has been detected; at z = 2.286, it corresponds to a rest wavelength of 370 microns. From the entire continuum spectrum we estimate a dust temperature of 80 K, and from the optically thin radiation at 370 microns (rest frame) we find a dust mass of 2.5 X 10^8^ h^-2^ M_sun_. For the H_2_ mass of 1 X 10^11^ h^-2^ M_sun_ implied by the CO line luminosity, this yields a ratio of the mass of gas (H_2_ + He) to warm dust of 500, which is surprisingly normal for a galaxy at z = 2.3. It is the same value as observed in the central regions of nearby luminous galaxies that have solar metallicity. The ratio of observed CO and 370 microns (restframe) luminosities in 10214 + 4724, essentially the gas-to-dust mass ratio, is the same as in nearby galaxies. Hence, In this galaxy, most of the heavy elements have already been produced, at nearly present-day abundances.