The Baryonic Content of Galaxies Mapped by MaNGA and the Gas Around Them

TL;DR

This study maps the gas around nearby galaxies using absorption lines from background quasars, revealing how gas properties like metallicity and kinematics relate to galaxy structure and outflows.

Contribution

It provides the first detailed comparison of circumgalactic medium properties with galaxy maps from integral field spectroscopy for a sample of 14 galaxies.

Findings

Neutral gas co-rotates with galaxy disks out to ~10 R_e.

Lower metallicity and H I density at lower galactic elevation angles.

Higher elevation sight lines show signs of outflows and higher ionization.

Abstract

We analyze the cool gas in and around 14 nearby galaxies (at $z$$<$0.1) mapped with the SDSS-IV MaNGA survey by measuring absorption lines produced by gas in spectra of background quasars/AGN at impact parameters of 0-25 effective radii from the galaxy center. Using HST/COS, we detect absorption at the galaxy redshift and measure or constrain column densities of neutral (H I, N I, O I, Ar I), low-ionization (Si II, S II, C II, N II Fe II), and high-ionization (Si III, Fe III, N V, O VI) species for 11 galaxies. We derive the ionization parameter and ionization-corrected metallicity using CLOUDY photo-ionization models. The H I column density ranges from $\sim$$10^{13}$ to $\sim$$10^{20}\,{\rm cm^{-2}}$ and decreases with impact parameter for $r \ge R_{e}$. Galaxies with higher stellar mass have weaker H I absorption. Comparing absorption velocities with MaNGA radial velocity maps of ionized gas line emissions in galactic disks, we find that the neutral gas seen in absorption co-rotates with the disk out to $\sim$10 $R_{e}$. Sight lines with lower elevation angles show lower metallicities, consistent with the metallicity gradient in the disk derived from MaNGA maps. Higher elevation angle sight lines show higher ionization, lower H I-column density, super-solar metallicity, and velocities consistent with the direction of galactic outflow. Our data offer the first detailed comparisons of CGM properties (kinematics and metallicity) with extrapolations of detailed galaxy maps from integral field spectroscopy; similar studies for larger samples are needed to more fully understand how galaxies interact with their CGM.