The Quasar Pairs Environment at z ~ 0.5

We analyze the environment of a sample of 20 quasar physical pairs at 0.4<z<0.65 in order to investigate the link between QSO activity and their environments. In particular we aim to explore if QSO that are embedded the same galaxy environment (projected distance < 0.5 Mpc) inhabit different environments than isolated QSO of similar luminosity. The galaxy environments of QSO pairs as derived from SDSS imaging data is compared with a larger sample of isolated QSO matched in terms of redshift and luminosityFrom the comparison of the two samples we find the the galaxy density at 250 kpc from the QSO that are in pairs is about a factor 2 larger than that of isolated QSO. In addition we also complement these imaging study with high quality optical spectroscopy gathered at GTC in La Palma to get info on the dynamic of the systemsImplications of these results based on a small (but “complete”) sample are briefly discussed.