On the Presence of a Universal Acceleration Scale in Elliptical Galaxies

Abstract

Dark matter phenomena in rotationally supported galaxies exhibit a characteristic acceleration scale of g †  ≈ 1.2 × 10 −10  m s −2 . Whether this acceleration is a manifestation of a universal scale, or merely an emergent property with an intrinsic scatter, has been debated in the literature. Here we investigate whether a universal acceleration scale exists in dispersion-supported galaxies using two uniform sets of integral field spectroscopy (IFS) data from SDSS-IV MaNGA and ATLAS 3D . We apply the spherical Jeans equation to 15 MaNGA and 4 ATLAS 3D slow-rotator E0 (i.e., nearly spherical) galaxies. Velocity dispersion profiles for these galaxies are well determined with observational errors under control. Bayesian inference indicates that all 19 galaxies are consistent with a universal acceleration of  m s −2 . Moreover, all 387 data points from the radial bins of the velocity dispersion profiles are consistent with a universal relation between the radial acceleration traced by dynamics and that predicted by the observed distribution of baryons. This universality remains if we include 12 additional non-E0 slow-rotator elliptical galaxies from ATLAS . Finally, the universal acceleration from MaNGA and ATLAS 3D is consistent with that for rotationally supported galaxies, so our results support the view that dark matter phenomenology in galaxies involves a universal acceleration scale.