Quasars Do Not Live in Merging Systems: No Enhanced Merger Rate at z≲0.8

We tackle the long-standing question “what is the relevance of major mergers and interactions as triggering mechanisms for AGN activity?” We study a sample of 83 quasars over z ~ 0.3-1.0 with high-resolution HST/ACS imaging in the F814W (broad I) band in the COSMOS field (Scoville et al. 2007), detected by their X-ray emission in the XMM-Newton survey (Hasinger et al. 2007). We perform a visual analysis of their morphologies, looking for signatures of merging and interactions in their host galaxies that could potentially be related to the AGN fueling mechanism. To get the best possible picture of the host galaxies, we remove the bright quasar by modeling each of them as a Sersic surface brightness profile plus a central point source, through a 2-D parametric fit.