MaNGA DynPop – III. Stellar dynamics versus stellar population relations in 6000 early-type and spiral galaxies: Fundamental Plane, mass-to-light ratios, total density slopes, and dark matter fractions

Abstract

ABSTRACT We present dynamical scaling relations, combined with the stellar population properties, for a subsample of about 6000 nearby galaxies with the most reliable dynamical models extracted from the full Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) sample of 10 000 galaxies. We show that the inclination-corrected mass plane for both early-type galaxies (ETGs) and late-type galaxies (LTGs), which links dynamical mass, projected half-light radius Re, and the second stellar velocity moment σe within Re, satisfies the virial theorem and is even tighter than the uncorrected one. We find a clear parabolic relation between $\lg (M/L)_{\rm e}$, the total mass-to-light ratio (M/L) within a sphere of radius Re, and $\lg \sigma _{\rm e}$, with the M/L increasing with σe and for older stellar populations. However, the relation for ETGs is linear and the one for the youngest galaxies is constant. We confirm and improve the relation between mass-weighted total density slopes $\overline{\gamma _{_{\rm T}}}$ and σe: $\overline{\gamma _{_{\rm T}}}$ become steeper with increasing σe until $\lg (\sigma _{\rm e}/{\rm km\, s^{-1}})\approx 2.2$ and then remain constant around $\overline{\gamma _{_{\rm T}}}\approx 2.2$. The $\overline{\gamma _{_{\rm T}}}\!-\!\sigma _{\rm e}$ variation is larger for LTGs than ETGs. At fixed σe the total density profiles steepen with galaxy age and for ETGs. We find generally low dark matter fractions, median fDM(<Re) = 8 per cent, within a sphere of radius Re. However, we find that fDM(<Re) depends on σe better than stellar mass: dark matter increases to a median fDM(<Re) = 33 per cent for galaxies with $\sigma _{\rm e}\lesssim 100$ km s−1. The increased fDM(<Re) at low σe explains the parabolic $\lg (M/L)_{\rm e}\!-\!\lg \sigma _{\rm e}$ relation.