Probing the circumgalactic medium of active galactic nuclei with background quasars

We performed a detailed study of the extended cool gas, traced by MgII absorption [$W_r(2796)\ge 0.3$~{\AA}], surrounding 14 narrow-line active galactic nuclei (AGNs) at 0.12<z<0.22 using background quasar sight-lines. The background quasars probe the AGNs at projected distances of $60\leq D\leq265$kpc\mathrm{.}Wefindthat,between$100\leq D\leq200$~kpc, AGNs appear to have lower MgII gas covering fractions (0.09${}_{-0.08}^{+0.18}$) than quasars (0.47${}_{-0.15}^{+0.16}$) and possibly lower than in active field galaxies (0.25${}_{-0.09}^{+0.11}$). We do not find a statistically significant azimuthal angle dependence for the MgII covering fraction around AGNs, though the data hint at one. We also study the down-the-barrel' outflow properties of the AGNs themselves and detect intrinsic NaID absorption in 8/8 systems and intrinsic MgII absorption in 2/2 systems, demonstrating that the AGNs have significant reservoirs of cool gas. We find that 6/8 NaID and 2/2 MgII intrinsic systems contain blueshifted absorption with $\Delta v>50$ km/s, indicating outflowing gas. The 2/2 intrinsic MgII systems have outflow velocities a factor of $\sim4$ higher than the NaID outflow velocities. Our results are consistent with AGN-driven outflows destroying the cool gas within their halos, which dramatically decreases their cool gas covering fraction, while star-burst driven winds are expelling cool gas into their circumgalactic media (CGM). This picture appears contrary to quasar--quasar pair studies which show that the quasar CGM contains significant amounts of cool gas whereas intrinsic gas found down-the-barrel’ of quasars reveals no cool gas. We discuss how these results are complementary and provide support for the AGN unified model.