Comment on "Multiscatter stellar capture of dark matter"

Bramante, Delgado, and Martin [Phys. Rev. D96, 063002(2017)., hereafter BDM17] extended the analytical formalism of dark matter (DM) capture in a very important way, which allows, in principle, the use of compact astrophysical objects, such as neutron stars (NS), as dark matter detectors. In this comment, we point out the existence of a region in the dark matter neutron scattering cross section $(\sigma_{nX})$ vs. dark matter mass $(m_{X})$ where the constraining power of this method is lost. This corresponds to a maximal temperature ($T_{crit}$) the NS has to have, in order to serve as a dark matter detector. In addition, we point out several typos and errors in BDM17 that do not affect drastically their conclusions. Moreover, we provide semi-analytical approximations for the total capture rates of dark matter particle of arbitrary mass for various limiting regimes. Those analytical approximations are used to validate our numerical results.