KBSS-InCLOSE I: Design and First Results from the Inner CGM of QSO Line Of Sight Emitting Galaxies at z~2-3

TL;DR

This paper introduces the KBSS-InCLOSE survey, which studies the inner circumgalactic medium of galaxies at redshifts 2-3 by combining deep IFU and NIR spectroscopy, revealing insights into galaxy-CGM interactions and metal enrichment.

Contribution

It presents the design, methodology, and first results of the KBSS-InCLOSE survey, including discovery of new galaxies and analysis of their CGM and ISM properties at high redshift.

Findings

G1's CGM is metal poor and less evolved than its ISM.

N1's CGM and ISM have comparable abundances.

G1's CGM shows evidence of hot, metal-rich outflows.

Abstract

We present the design and first results of the Inner Circumgalactic Medium (CGM) of QSO Line of Sight Emitting galaxies at $z\sim 2-3$, KBSS-InCLOSE. The survey will connect galaxy properties (e.g., stellar mass $M_*$, interstellar medium ISM metallicity) with the physical conditions of the inner CGM (e.g., kinematics, metallicity) to directly observe the galaxy-scale baryon cycle. We obtain deep Keck/KCWI optical IFU pointings of Keck Baryonic Structure Survey (KBSS) QSOs to discover new star-forming galaxies at small projected distances $b\lesssim12"$ (98 kpc, $\overline{z}=2.3$), then obtain follow-up Keck/MOSFIRE NIR spectra to confirm their redshifts. We leverage KBSS images and Keck/HIRES QSO spectra to model stellar populations and inner CGM absorption. In this paper, we analyze two QSO fields and discover more than 15 new galaxies with KCWI, then use MOSFIRE for two galaxies Q2343-G1 ($z=2.43$; G1) and Q2233-N1 ($z=3.15$; N1), which are both associated with Damped Lyman Alpha absorbers. We find that G1 has typical $M_*$,UV/optical emission properties. N1 has lower $M_*$ with very strong nebular emission. We jointly analyze neutral phase CGM and ionized ISM in N/O (for the first time at this $z$), dust extinction, and high-ionization CGM finding that: G1's CGM is metal poor and less evolved than its ISM, while N1's CGM and ISM abundances are comparable; their CGM shows $\sim1$ dex less dust extinction than the ISM; and G1's CGM has direct evidence of hot, metal-rich galactic outflow ejecta. These findings support that metals and dust are driven into the CGM from outflows, but may also be e.g., stripped ISM gas or satellite enrichment. The full KBSS-InCLOSE sample will explore these scenarios.