New constraints on the dark matter density profiles of dwarf galaxies
  from proper motions of globular cluster streams
  The central density profiles in low-mass and dwarf galaxy halos depend
strongly on the nature of dark matter. Recently, in Malhan et al. (2021), we
employed N-body simulations to show that the cuspy cold dark matter (CDM)
subhalos predicted by cosmological simulations can be differentiated from cored
subhalos using the properties of accreted globular cluster streams -- those
stellar streams produced from the tidal stripping of globular clusters that
initially evolved within their parent dwarf galaxies and only later merged with
the Milky Way. In particular, we previously found that clusters that are
accreted within cuspy CDM subhalos produce streams with larger physical widths
and higher line-of-sight velocity dispersions as compared to those streams that
accrete inside cored subhalos. Here, we use the same suite of simulations to
demonstrate that the dispersion in the tangential velocity of streams
($\sigma_{v_\mathrm{Tan}}$) is another parameter that is also sensitive to the
central DM density profile of their parent dwarfs. We find that globular
clusters that were accreted from cuspy CDM subhalos produce streams with larger
$\sigma_{v_\mathrm{Tan}}$ than those that were accreted inside cored subhalos.
Furthermore, we use Gaia EDR3 observations of multiple GC streams to compare
their $\sigma_{v_\mathrm{Tan}}$ values with simulations. This comparison
indicates that the five observed streams we analyze are more likely to be
associated with globular clusters of `accreted' rather than `in situ' origin.
We also find evidence that the progenitor globular clusters of these streams
were probably accreted inside cored DM subhalos (with $M_{\rm subhalo}\buildrel
> \over \sim$ $10^{8-9}M_{\odot}$).
