SIMBAD references

We investigate the extent and the properties of the Mgii 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 < 200kpc in the redshift range 0.5 ≲ z ≲ 1.6. In the transverse direction, we detect 18 Mgii absorbers associated with the foreground quasars, while no absorption system originated by the gas surrounding the quasar itself is found along the line of sight. This suggests that the quasar emission induces an anisotropy in the absorbing gas distribution. Our observations indicate that the covering fraction (fC) of Mgii absorption systems with rest-frame equivalent width Wr(λ2796) > 0.3Å ranges from fC ∼ 1.0 at pd ≲ 65kpc to fC ∼ 0.2 at pd ≳ 150kpc, and appears to be higher than that for galaxies. Our findings support a scenario where the luminosity/mass of the host galaxies affect the extent and the richness of the absorbing Mgii circumgalactic medium.