Observations of 1.3 millimeter continuum emission from the centers of galaxies

Abstract

The authors have searched for 1.3 mm continuum emission toward the centers of eight galaxies and detected it with a signal-to-noise ratio greater than 3 in three: NGC 1068, Arp 220, and M82. M51 and NGC 253 were possibly detected, and negative results were obtained for IC 342, NGC 6574, and NGC 4038. The authors concluded that the emission at this wavelength is from dust at modest temperatures (T<SUB>d</SUB> ≈ 20K). Gas masses calculated from the 1.3 mm emission are in fair agreement with the estimated amount of H<SUB>2</SUB>. It is shown that gas masses estimated from millimeter continuum observations are accurate to about a factor of 5. The authors use the gas masses and the observed far-infrared luminosity to estimate the efficiency of star formation. For most galaxies, this efficiency is approximately equal to 1%.