Gone after one orbit: How cluster environments quench galaxies
  The effect of galactic orbits on a galaxy's internal evolution within a
galaxy cluster environment has been the focus of heated debate in recent years.
To understand this connection, we use both the $(0.5 \,$Gpc)$^3$ and the
Gpc$^3$ boxes from the cosmological hydrodynamical simulation set Magneticum
Pathfinder. We investigate the velocity-anisotropy, phase space, and the
orbital evolution of up to $\sim 5 \cdot 10^{5}$ resolved satellite galaxies
within our sample of 6776 clusters with $M_{\mathrm{vir}} > 10^{14} \,
\mathrm{M_{\odot}}$ at low redshift, which we also trace back in time. In
agreement with observations, we find that star-forming satellite galaxies
inside galaxy clusters are characterised by more radially dominated orbits,
independent of cluster mass. Furthermore, the vast majority of star-forming
satellite galaxies stop forming stars during their first passage. We find a
strong dichotomy both in line-of-sight and radial phase space between
star-forming and quiescent galaxies, in line with observations. The tracking of
individual orbits shows that the star-formation of almost all satellite
galaxies drops to zero within $1 \, \mathrm{Gyr}$ after in-fall. Satellite
galaxies that are able to remain star-forming longer are characterised by
tangential orbits and high stellar mass. All this indicates that in galaxy
clusters the dominant quenching mechanism is ram-pressure stripping.
