Molecular Cloud Content of Early-Type Galaxies. V. CO in Elliptical Galaxies

摘要

A survey of CO emission in 29 far-IR selected elliptical galaxies resulted in 16detections, of which 3 remain tentative. The molecular gas masses range from 2 X 10(exp 6) solar masses to 1 X 10(exp 9) solar masses, and appear to be unrelated to the underlying stellar population. This suggests an external origin of the gas. Most of the elliptical galaxies with a molecular gas component have a gas-to-dust mass ratio of about 700, where dust masses are derived from the Infrared Astronomy Satellite (IRAS) fluxes, but some appear to have a ratio as low as 50. A small apparent gas-to-dust mass ratio is also found for some late-type galaxies, and is correlated with a low dust temperature.