The MASSIVE Survey. XII. Connecting Stellar Populations of Early-type Galaxies to Kinematics and Environment

Abstract

We measure the stellar populations as a function of the radius for 90 early-type galaxies (ETGs) in the MASSIVE survey, a volume-limited integral-field spectroscopic (IFS) galaxy survey targeting all northern-sky ETGs with an absolute K-band magnitude of M _K < -25.3 mag or a stellar mass of {M}_* ≳ 4× {10}¹¹ {M}_⊙ , within 108 Mpc. We are able to measure reliable stellar population parameters for individual galaxies out to 10-20 kpc (1-3 R _e ) depending on the galaxy. Focusing on ∼R _e (∼10 kpc), we find significant correlations between the abundance ratios, σ, and {M}^* at a large radius, but we also find that the abundance ratios saturate in the highest-mass bin. We see a strong correlation between the kurtosis of the line-of-sight velocity distribution (h4) and the stellar population parameters beyond R _e . Galaxies with higher radial anisotropy appear to be older, with metal-poorer stars and enhanced [α/Fe]. We suggest that the higher radial anisotropy may derive from more accretion of small satellites. Finally, we see some evidence for correlations between environmental metrics (measured locally and on >5 Mpc scales) and the stellar populations, as expected if satellites are quenched earlier in denser environments.