The SLUGGS Survey: The mass distribution in early-type galaxies within
  five effective radii and beyond
  We study mass distributions within and beyond 5~effective radii ($R_{\rm e}$)
in 23 early-type galaxies from the SLUGGS survey, using their globular cluster
(GC) kinematic data. The data are obtained with Keck/DEIMOS spectrograph, and
consist of line-of-sight velocities for ~$3500$ GCs, measured with a high
precision of ~15 $\rm km\ s^{-1}$ per GC and extending out to $~13 R_{\rm e}$.
We obtain the mass distribution in each galaxy using the tracer mass estimator
of Watkins et al. and account for kinematic substructures, rotation of the GC
systems and galaxy flattening in our mass estimates.
  The observed scatter between our mass estimates and results from the
literature is less than 0.2 dex. The dark matter fraction within $5R_{\rm e}$
($f_{\rm DM}$) increases from ~$0.6$ to ~$0.8$ for low- and high-mass galaxies,
respectively, with some intermediate-mass galaxies ($M_*{\sim}10^{11}M_\odot$)
having low $f_{\rm DM}\sim0.3$, which appears at odds with predictions from
simple galaxy models. We show that these results are independent of the adopted
orbital anisotropy, stellar mass-to-light ratio, and the assumed slope of the
gravitational potential. However, the low $f_{\rm DM}$ in the ~$10^{11}M_\odot$
galaxies agrees with the cosmological simulations of Wu et al. where the
pristine dark matter distribution has been modified by baryons during the
galaxy assembly process. We find hints that these $M_*\sim10^{11}M_\odot$
galaxies with low $f_{\rm DM}$ have very diffuse dark matter haloes, implying
that they assembled late. Beyond $5R_{\rm e}$, the $M/L$ gradients are steeper
in the more massive galaxies and shallower in both low and intermediate mass
galaxies.
