Orbital decay of Globular Clusters in the galaxy with little dark matter
  Recently, \cite{vanDokkum2018} have presented an important discovery of an
ultra diffuse galaxy, NGC1052-DF2, with a dark matter content significantly
less than predicted from its stellar mass alone. The analysis relies on
measured radial velocities of 10 Globular Clusters (GCs), of estimated
individual masses of a few $ \times 10^6 M_\odot$. This is about $1\%$ of the
inferred mass of NGC1052-DF2 of $2\times 10^8 M_\odot$ within a half-light
radius, $R_\mathrm{e}=2.2\, \mathrm{kpc}$. The large relative mass and the old
age of these objects imply that they might be susceptible to orbital decay by
dynamical friction. Using analytic estimates and N-body simulations of an
isolated system matching the inferred mass profile of NGC1052-DF2, we show that
orbits of the most massive GCs should already have decayed on a time scale of a
few Gyrs. These findings should help in constraining mass profile and formation
scenarios of NGC1052-DF2.
