Cold molecular gas in cooling flow clusters of galaxies

The results of a CO line survey in central cluster galaxies with cooling flows are presented. Cold molecular gas is detected with the IRAM 30 m telescope, through CO( 1 - 0) and CO( 2 - 1) emission lines in 6 - 10 among 32 galaxies. The corresponding gas masses are between 3 x 10(8) and 4 x 10(10) M. These results are in agreement with recent CO detections by Edge ( 2001). A strong correlation between the CO emission and the Halpha luminosity is also confirmed. Cold gas exists in the center of cooling flow clusters and these detections may be interpreted as evidence of the long searched for very cold residual of the hot cooling gas.