Distances of Centaurus A and M83 galaxies

In this study, we analyze the dynamics of the Centaurus A (CenA) and M83 galaxies, along with their associated dwarf companions identified via Tip of the Red Giant Branch (TRGB) distance measurements, to constrain both the group mass and the local value of H0. By examining the motions of these galaxies relative to the system's barycenter, we apply both the minor and major infall models, which provide bounds on the true radial velocity dispersion.

From the overlap from these approaches, we obtain a virial mass estimate of (7.3+/-2.0)x10^12^M_{sun}_ and a Hubble flow-based mass of (2.6+/-1.4)x10^12^M_{sun}_. Modeling the cold Hubble flow around the group center-of-mass, we derive a corresponding value of the Hubble constant as (64.0+/-4.6)km/s/Mpc. These results offer an independent, dynamically motivated constraint on the local value of H0, explicitly accounting for the impact of peculiar velocities in the nearby Universe.