Study of gravitational fields and globular cluster systems of early-type
  galaxies
  (abridged)
  Context. Gravitational fields at the outskirts of early-type galaxies (ETGs)
are difficult to constrain observationally. It thus remains poorly explored how
well the LCDM and MOND hypotheses agree with ETGs.
  Aims. This led us to gather a large sample of ETGs and examine homogeneously
which dark matter halos they occupy, whether the halos follow the theoretically
predicted stellar-to-halo mass relation (SHMR) and the halo mass-concentration
relation (HMCR), whether ETGs obey MOND and the radial acceleration relation
(RAR) observed for late-type galaxies (LTGs), and finally whether LCDM or MOND
perform better in ETGs.
  Methods. We employed Jeans analysis of radial velocities of globular clusters
(GCs). We analysed nearly all ETGs having more than about 100 archival GC
radial velocity measurements. The GC systems of our 17 ETGs extend mostly over
ten effective radii. A LCDM simulation of GC formation helped us to interpret
the results.
  Results. Successful LCDM fits are found for all galaxies, but compared to the
theoretical HMCR and SHMR, the best-fit halos usually have concentrations that
are too low and stellar masses that are too high for their masses. This might
be because of tidal stripping of the halos or because ETGs and LTGs occupy
different halos. Most galaxies can be fitted by the MOND models successfully as
well, but for some of the galaxies, especially those in centers of galaxy
clusters, the observed GC velocity dispersions are too high. This might be a
manifestation of the additional dark matter that MOND requires in galaxy
clusters. Additionally, we find many signs that the GC systems were perturbed
by galaxy interactions. Formal statistical criteria prefer the best-fit LCDM
models over the MOND models, but this might be due to the higher flexibility of
the LCDM models. The MOND approach can predict the GC velocity dispersion
profiles better.
