Tidal streams around galaxies in the SDSS DR7 archive

Abstract

Context. Models of hierarchical structure formation predict the accretion of smaller satellite galaxies onto more massive systems and this process should be accompanied by a disintegration of the smaller companions visible, e.g., in tidal streams. Aims. In order to verify and quantify this scenario we have developed a search strategy for low surface brightness tidal structures around a sample of 474 galaxies using the Sloan Digital Sky Survey DR7 archive. Methods. Calibrated images taken from the SDSS archive were processed in an automated manner and visually inspected for possible tidal streams. Results. We were able to extract structures at surface brightness levels ranging from \sim 24 down to 28 mag arcsec-2. A significant number of tidal streams was found and measured. Their apparent length varies as they seem to be in different stages of accretion. Conclusions. At least 6% of the galaxies show distinct stream like features, a total of 19% show faint features. Several individual cases are described and discussed.