Probing the Inner Circumgalactic Medium and Quasar Illumination around the Reddest Extremely Red Quasar (ERQ)

Dusty quasars might be in a young stage of galaxy evolution with prominent quasar feedback. We study a population of luminous, extremely red quasars at redshifts z ~ 2-4 that has a suite of extreme spectral properties that may all be related to exceptionally powerful quasar-driven outflows. We present Keck/KCWI observations of the reddest known ERQ, at z = 2.3184, with an extremely fast [OIII]5007 outflow at ~6000 km s^-1. The Lyalpha halo spans ~100 kpc. The halo is kinematically quiet, with spatially-integrated velocity dispersion ~300 km s^-1 and no broadening above the dark matter circular velocity down to the spatial resolution ~6 kpc from the quasar. We detect spatially-resolved HeII1640 and CIV1549 emissions with kinematics similar to the Lyalpha halo and a narrow component in the [OIII]5007. Quasar reddening acts as a coronagraph allowing views of the innermost halo. A narrow Lyalpha spike in the quasar spectrum is inner halo emission, confirming the broad CIV1549 in the unresolved quasar is blueshifted by 2242 km s^-1 relative to the halo frame. Our measurements suggest the inner halo region is dominated by past/moderate-speed outflow and the outer halo region is dominated by inflow. The high central concentration of the surface brightness and the circularly symmetric appearance of the inner halo are consistent with the ERQ being young. The HeII/Lyalpha ratio of the inner halo and the asymmetry level of the overall halo are dissimilar to Type II quasars, implying central ionizing photons can escape along the line of sight. We find no definitive evidence of quasar feedback on circumgalactic scales.

Finally, we will present preliminary analysis of Keck/OSIRIS observations of the [OIII]5007 emission.