The extent of the Mg II absorbing circumgalactic medium of quasars

We investigate the extent and the properties of the Mg II cool, low-density absorbing gas located in the halo and in the circumgalactic environment of quasars, using a sample of 31 projected quasar pairs with impact parameter pd < 200 kpc in the redshift range 0.5 ≲ z ≲ 1.6. In the transverse direction, we detect 18 Mg II absorbers associated with the foreground quasars, while no absorption system...