A search for CO emission in cooling flows

The NRAO 12 m telescope was used to search for CO emission from the centers of two elliptical galaxies and four clusters of galaxies rich in 10 to the 7th-10 to the 8th K gas. No CO emission was detected, and the 3(delta) upper limits are 1-2 x 10 to the 8th solar masses for elliptical galaxies and 1-6 x 10 to the 10th solar masses for the clusters. The cooling-flow model for the evolution of the hot gas predicts the rate at which cool gas, and eventually stars, are produced. If this model is correct, measurements indicate that the ratio of the CO mass to the star-formation rate is at least a half order of magnitude less than in the Galaxy; star formation occurs rapidly and efficiently. (Author)