  This study is aimed at investigating the dynamic evolution of the orbits of
stellar globular clusters (GCs). To integrate the orbits backward in time, the
authors use models of the time-varying potentials derived from cosmological
simulations, which are closest to the potential of the Galaxy. This allows for
estimating the probability of close passages (collisions) of GCs with respect
to each other and the Galactic center (GalC) in the Galaxy undergoing dynamic
changes in the past. To reproduce the dynamics of the Galaxy in time, five
potentials selected from the IllustrisTNG-100 large-scale cosmological
database, which are similar in their characteristics to the current physical
parameters of the Milky Way, are used. With these time-varying potentials, we
have reproduced the orbital trajectories of 143 GCs 10 Gyr back in time using
our original phi-GPU N-body code. Each GC was treated as a single physical
particle with the assigned position and velocity of the cluster center from the
Gaia DR2 observations. For each of the potentials, 1000 initial conditions were
generated with randomized initial velocities of GCs within the errors of the
observational data. In this study, we consider close passages to be passages
with a relative distance of less than 100 pc and a relative speed of less than
250 km/s. To select clusters that pass at close distances from the GalC, the
following criterion is applied based only on the relative distance: it must be
less than 100 pc. Applying the above criteria, the authors obtained
statistically significant rates of close passages of GCs with respect to each
other and to the GalC. It has been determined that GCs during their evolution
have approximately 10 intersecting trajectories with each other on the average
and approximately 3 to 4 close passages near the GalC in 1 Gyr at a distance of
50 pc for each of the chosen potentials.
