A Tip of the Red Giant Branch Distance of 22.1 ± 1.2 Mpc to the Dark Matter Deficient Galaxy NGC 1052–DF2 from 40 Orbits of Hubble Space Telescope Imaging

The large and diffuse galaxies NGC1052-DF2 NGC1052-DF4 have been found to very low dark matter content a population of luminous globular clusters. Accurate distance measurements are key interpreting these observations. Recently, the was be $20.0\pm 1.6$ Mpc by identifying tip red giant branch (TRGB) in 12 orbits Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) imaging. Here we present 40 HST ACS data use measure its TRGB. TRGB is readily apparent color-magnitude diagram. Using forward model that incorporates photometric uncertainties, find magnitude $m_{\rm F814W, TRGB} = 27.67 \pm 0.10$ mag. inferred $D_{\rm 22.1 1.2$ Mpc, consistent with previous surface brightness fluctuation distances bright elliptical galaxy NGC1052. new rules out idea some NGC1052-DF2's unusual properties can explained if it were at $\sim 13$ Mpc; instead, implies galaxy's clusters even more than had derived using 20 Mpc. from well-determined $2.1\pm 0.5$ significantly larger virial diameter We discuss implications formation scenarios external field effect, which has invoked explain intrinsic dynamics objects context modified Newtonian dynamics.