Massive disc galaxies in cosmological hydrodynamical simulations are too
  dark matter-dominated
  We investigate the disc-halo connection in massive (Mstar/Msun>5e10) disc
galaxies from the cosmological hydrodynamical simulations EAGLE and
IllustrisTNG, and compare it with that inferred from the study of HI rotation
curves in nearby massive spirals from the Spitzer Photometry and Accurate
Rotation Curves (SPARC) dataset. We find that discrepancies between the the
simulated and observed discs arise both on global and on local scales.
Globally, the simulated discs inhabit halos that are a factor ~4 (in EAGLE) and
~2 (in IllustrisTNG) more massive than those derived from the rotation curve
analysis of the observed dataset. We also use synthetic rotation curves of the
simulated discs to demonstrate that the recovery of the halo masses from
rotation curves are not systematically biased. We find that the simulations
predict dark-matter dominated systems with stellar-to-total enclosed mass
ratios that are a factor of 1.5-2 smaller than real galaxies at all radii. This
is an alternative manifestation of the `failed feedback problem', since it
indicates that simulated halos hosting massive discs have been too inefficient
at converting their baryons into stars, possibly due to an overly efficient
stellar and/or AGN feedback implementation.
