CO emission associated with a cooling flow
The existence of cooling flows in the center of galaxy clusters has always been a puzzle, and in particular the fate of the cooling gas, since the presence of cold gas has never been proven directly. X-ray data from the satellites Chandra and XMM-Newton have constrained the amount of cooling, and it was realized that feedback and heating from a central AGN and its jets could reduce the amount of cold gas. Recently, a few central galaxies of cooling flow clusters have been detected in the CO lines. For the first time, we show IRAM interferometer maps of CO(1-0) and CO(2-1) emission in a cooling flow, showing a clear association of the cold gas (at about 20K) with the cooling flow. This shows that although the AGN provides a feedback heating, the cooling phenomenon does occur, with about the expected rate.