Constraining dark halo potentials with tidal tails

We present an extensive parameter survey of the influence of halo mass prof iles on the development of tidal tails in interacting disk galaxies. We mod el the galaxies using a fixed exponential disk with a central bulge and var y the halo potential over a range of parameters using both the Hernquist an d Navarro, Frenk, & White mass distributions, probing the effect of the hal o mass, extent, and concentration. We examine the consistency of the result s against both observational and theoretical constraints on halo profiles a nd comment on the failures and weaknesses of different models. A galaxy wit h a rising or flat rotation curve dominated by the halo is inhibited from f orming a tidal tail unless the halo is abruptly cut off just beyond the dis k edge. Conversely, models with declining rotation curves-resulting either from compact, low-mass halos or from massive disk components in low-concent ration dark halos-produce tidal tails very similar to those observed in wel l-studied interacting systems. As argued by Springel & White, a unifying, q uantitative relation for all cases is that the ratio of the escape velocity to the circular velocity at around the solar radius must be nu(e)/nu(c) le ss than or equal to 2.5 for tidal tails to be produced. The galaxy models t hat appear to fit most of the observational constraints are those that have disk-dominated rotation curves and low-concentration halos. We discuss our results in a cosmological context using recent studies that link halo prop erties to cosmological models.