Nora Loiseau ESA XMM-Newton I am an observational astronomer working for the XMM-Newton Users Support Group. I have been working in several subjects quite apart from each other, but my main interest since I made my PhD on the SMC, is the study of interacting galaxies. By means of lines observations, one gets three dimensional information on the structure of the interacting galaxies and on the flows of gas leading to starburst activity in the bars ends, circumnuclear rings, etc. and/or feeding an active nucleus, also leading to the formation of tails and bridges. I have observed the HI 21cm line in the Magellanic Clouds, Bridge and Stream. I performed CO millimeter lines observations of M82 (first extragalactic detection of 13CO(2-1)), and of starburst and active interacting galaxies selected by their high IRAS flux. I also performed optical lines observations with the Fabry-Perot interferometer Taurus II at the 4.2m telescope at La Palma. In the interacting/barred/active/tailed galaxy NGC3227, we found optical and UV (XMM-OM) emission associated with the extra long HI tail, possible origin of a new dwarf galaxy. With Elena Jimenez, Matteo Guainazzi, Maria Santos and other collaborators we are presently analysing XMM and Chandra data of a sample of interacting pairs of similar sized galaxies. Previous X-ray observations showed a few cases of pairs of galaxies of similar size that host an AGN each. We would like to determine the critical parameters, like the separation between the galaxies, which would be relevant for the switching of the two active nucleus, during a certain stage of the merging of two interacting galaxies.