Tidal disruption of star clusters in galaxy formation simulations
  We investigate the evolution of the tidal field experienced by massive star
clusters using cosmological simulations of Milky Way-sized galaxies. Clusters
in our simulations experience the strongest tidal force in the first few
hundred Myr after formation, when the maximum eigenvalue of the tidal tensor
reaches several times $10^4$ Gyr$^{-2}$. After about 1 Gyr the tidal field
plateaus at a lower value, with the median $\lambda_{\rm m} \sim 3 \times 10^3$
Gyr$^{-2}$. The fraction of time clusters spend in high tidal strength
($\lambda_{\rm m} > 3 \times 10^4$ Gyr$^{-2}$) regions also decreases with
their age from $\sim$20% immediately after formation to less than 1% after 1
Gyr. At early ages both the in situ and ex situ clusters experience similar
tidal fields, while at older ages the in situ clusters in general experience
stronger tidal field due to their lower orbits in host galaxy. This difference
is reflected in the survival of clusters: we looked into cluster disruption
calculated in simulation runtime and found that ex situ star clusters of the
same initial mass typically end up with higher bound fraction at the last
available simulation snapshot than the in situ ones.
