Circumgalactic Metal Emission at z ~ 2–3 with the Keck Cosmic Web Imager

We present initial results from the Keck Cosmic Web Imager (KCWI) subsample of the Keck Baryonic Structure Survey (KBSS). KBSS-KCWI comprises 152 targets at z ~ 2–3 drawn from KBSS fields, of which 140 are star forming galaxies and 12 are AGN-host galaxies. The integral field spectroscopy (IFS) provided by Keck/KCWI (R ~ 2000) reveals the spatial distribution of rest-frame UV emission in the circumgalactic media (CGM) of these galaxies. With KBSS-KCWI, we observe both resonant (e.g. Lyα) and non-resonant emission; we focus in particular on the latter since non-resonant transitions directly trace the morphology of metal-enriched galactic outflows at high optical depths. In addition, high-ionization collitionally excited transitions of metal species dominate the gas cooling at the peak of the cooling curve, and their strong temperature sensitivity provides a robust probe for the kinematics of the warm/hot phase of the CGM. We present this KBSS-KCWI IFS in the form of three-dimensional data cubes and in cylindrically deprojected two-dimensional spectra which show the radial dependence of metallic features. These data comprise the most sensitive measurements ever made on the connection between host galaxies and their CGM; going forward, KBSS ancillary data (e.g. spectra from KBSS-MOSFIRE and KBSS-LRIS) will strengthen this connection with complete spectral coverage for these objects from the rest-frame UV to the rest-frame optical.