We construct the Schwarzschild dynamical models for 11 early-type galaxies
with the SAURON and Mitchell stellar IFUs out to 2β4Reβ, and
construct dynamical models with combined stellar and HI kinematics for a
subsample of 4 galaxies with HI velocity fields out to 10Reβ
obtained from the Westerbork Synthesis Radio Telescope, thus robustly obtaining
the dark matter content out to large radii for these galaxies. Adopting a
generalised-NFW dark matter profile, we measure an NFW-like density cusp in the
dark matter inner slopes for all sample galaxies, with a mean value of
1.00Β±0.04 (rms scatter 0.15). The mean dark matter fraction for the
sample is 0.2 within 1Reβ, and increases to 0.4 at 2Reβ, and 0.6 at 5Reβ. The dark matter fractions within
1Reβ of these galaxies are systematically lower than the
predictions of both the TNG-100 and EAGLE simulations. For the dark matter
fractions within 2Reβ and 5Reβ, 40% and 70% galaxies
are 1βΟ consistent with either the TNG-100 or the EAGLE predictions,
while the remaining 60% and 30% galaxies lie below the 1βΟ region.
Combined with 36 galaxies with dark matter fractions measured out to 5Reβ in the literature, about 10% of these 47 galaxies lie below the
3βΟ region of the TNG-100 or EAGLE predictions.Comment: 15 pages, 9 figures, accepted by MNRA