Interpreting debris from satellite disruption in external galaxies

We examine the detectability and interpretation of debris trails caused by satellite disruption in external galaxies using semianalytic approximations for the dependence of streamer length, width, and surface brightness on sa tellite and primary galaxy characteristics. The semianalytic method is test ed successfully against N-body simulations and then applied to three repres entative astronomical applications. First, we show how streamer properties can be used to estimate mass-to-light ratios Y and streamer ages of totally disrupted satellites, and we apply the method to the stellar arc in NGC 59 07. Second, we discuss how the lack of observed tidal debris around a satel lite can provide an upper limit on its mass-loss rate and, as an example, d erive the implied limits on mass-loss rates for M32 and NGC 205 around Andr omeda. Finally, we point out that a statistical analysis of streamer proper ties might be applied to test and refine cosmological models of hierarchica l galaxy formation, and we use the predicted debris from a standard A cold dark matter realization to test the feasibility of such a study. Using the Local Group satellites and the few known examples of debris trails in the G alaxy and in external systems, we estimate that the best current techniques could characterize the brightest (R < 29 mag arcsec(-2)) portions of the y oungest (3 dynamical periods) debris streamers. If systematics can be contr olled, planned large-aperture telescopes such as CELT and OWL may allow fai nter trails to be detected routinely and thus may be used for statistical s tudies such as those required for tests of galaxy formation.