Subaru Deep Imaging of Interacting Galaxies

Abstract

We present deep optical images obtained with the Subaru Prime Focus Camera (Suprime-Cam) for nearby interacting galaxies. New tidal structures are revealed in many systems: remarkable examples include a northern faint extension of the Antennae, a large extension of Arp 220 – doubling the size from the previously-known, and a new tidal tail of Mrk 231. These extended features constrain the orientations and orbits of progenitor galaxies; the large extensions indicate that their rotations were retrograde with respect to the orbits. The orientations of the progenitors may constrain the timescale that merging completes, the duration of gravitational perturbation, and the timescale of gas fueling to galactic centers. This introduces an additional parameter (i.e. orientation of spin) in categorizing the evolutionary sequence of merging based on optical images.