A New Formation Scenario for the Milky Way Cluster NGC2419
  We present a new formation scenario for NGC2419, which is one of the most
luminous,one of the most distant, and as well one of the most extended globular
clusters of the Milky Way. We propose that NGC2419 is the remnant of a merged
star cluster complex, which was possibly formed during an interaction between a
gas-rich galaxy and the Milky Way. To test this hypothesis, we performed
numerical simulations of 27 different models of star cluster complexes (CCs)
moving on a highly eccentric orbit in the Galactic halo. We vary the CC mass,
the CC size, and the initial distribution of star clusters in the CC to analyze
the influence of these parameters on the resulting objects. In all cases, the
vast majority of star clusters merged into a stable object. The derived
parameters mass, absolute V-band magnitude, effective radius, velocity
dispersion and the surface brightness profile are, for a number of models, in
good agreement with those observed for NGC2419. Despite the large range of CC
sizes, the effective radii of the merger objects are constrained to a
relatively small interval. A turnover in the r_eff vs. M_encl space leads to
degenerate states, i.e. relatively compact CCs can produce an object with the
same structural parameters as a more massive and larger CC. In consequence, a
range of initial conditions can form a merger object comparable to NGC2419
preventing us to pinpoint the exact parameters of the original CC, which formed
NGC2419. We conclude that NGC2419 can be well explained by the merged cluster
complex scenario. Some of the recently discovered stellar streams in the
Galactic halo might be related to the parent galaxy, which produced the cluster
complex in our scenario. Measurements of the proper motion of NGC2419 are
necessary to prove an association with one of the stellar streams.
