Wobbling galaxy spin axes in dense environments

We investigate the changes of galaxy spin orientation in dense environments using hydrodynamical cosmological zoom-in simulations for 17 galaxy clusters. This study reveals that the spin axes of satellite galaxies become more unstable when the satellites have lower initial $V/{\sigma}$, orbits with smaller pericenter distance, and higher merger rates after infall into the model clusters. The satellite galaxies involved in mergers after infall experience twice larger angular changes of spin axes than those without mergers. We also find that perturbation exerted by environments or neighboring galaxies strongly correlates with the stability of spin orientation and final $V/{\sigma}$. On the other hand, the size or stellar mass density of the satellites are not significantly affected by mergers or perturbation in cluster environments.