The kinematic connection between galaxies and dark matter haloes

Abstract

Using estimates of dark halo masses from satellite kinematics, weak gravitational lensing and halo abundance matching, combined with the Tully-Fisher (TF) and Faber-Jackson relations, we derive the mean relation between the optical, Vopt, and virial, V200, circular velocities of early- and late-type galaxies at redshift z≃ 0. For late-type galaxies, Vopt≃V200 over the velocity range Vopt= 90-260 km s-1, and is consistent with Vopt=Vmax,h[the maximum circular velocity of NFW dark matter haloes in the concordance Λ cold dark matter (Λ CDM) cosmology]. However, for early-type galaxies Vopt≠V200, with the exception of early-type galaxies with Vopt≃ 350 km s-1. This is inconsistent with early-type galaxies being, in general, globally isothermal. For low-mass (Vopt≲ 250 km s-1) early-types Vopt > Vmax,h, indicating that baryons have modified the potential well, while high-mass (Vopt > rsim 400 km s-1) early-types have Vopt