2010MNRAS.405.1723S

A new harassment model is presented that models the complex and dynamical tidal field of a Virgo-like galaxy cluster. The model is applied to small, late-type dwarf disc galaxies (of substantially lower mass than in previous harassment simulations) as they infall into the cluster from the outskirts. These dwarf galaxies are only mildly affected by high-speed tidal encounters with little or no observable consequences; typical stellar losses are <10per cent, producing very low surface brightness streams (mag/arcsec2) and a factor of 2 drop in dynamical mass-to-light ratio. Final stellar discs remain disc like, and dominated by rotation although often with tidally induced spiral structure. By means of Monte Carlo simulations, the statistically likely influences of harassment on infalling dwarf galaxies are determined. The effects of harassment are found to be highly dependent on the orbit of the galaxy within the cluster, such that newly accreted dwarf galaxies typically suffer only mild harassment. Strong tidal encounters, that can morphologically transform discs into spheroidals, are rare occurring in <15per cent of dwarf galaxy infalls for typical orbits of substructure within cold dark matter cluster mass haloes. For orbits with small apocentric distances (<250kpc), harassment is significantly stronger resulting is in complete disruption or heavy mass loss (>90per cent dark matter and >50per cent stellar), however, such orbits are expected to be highly improbable for newly infalling galaxies due to the deep potential well of the cluster.