MILLIMETER AND SUBMILLIMETER CONTINUUM EMISSION FROM EARLY-TYPE GALAXIES

Twenty-two early-type galaxies that were detected by IRAS have been searched for continuum emission at millimeter and submillimeter wavelengths using the James Clerk Maxwell Telescope (JCMT). IRAS was relatively insensitive to cold dust that emits primarily at these longer wavelengths. In this first survey we were able to detect or achieve useful limits on the emission from 14 of the 22 galaxies observed. From these data we estimate upper limits on the dust temperature and lower limits on the mass of dust within the JCMT beam. These results are compared with H I and CO data and with the blue luminosities of the galaxies. The results are consistent with a model where the dust-to-gas ratio is similar to the Galactic one, and the amount of cold dust is an order of magnitude greater than the amount of warm dust (as is also seen in our Galaxy). The total dust mass, normalized to the luminosity of the entire galaxy, is much lower than is found in spiral galaxies, as expected.