Intergalactic Cold Dust in the NGC 4631 System

We have detected extraplanar cold dust at distances out to > 10 kpc, situated in the halo of the interacting galaxy NGC 4631. Most of the extraplanar dust is closely associated with known HI spurs. In addition, a giant arc has been found that is linked to anomalies in the kinematical structure of the atomic gas. The morphological similarities with the HI features suggests that we see a track left behind by the interaction. Right in the zone where the dust trail crosses the disk the HI shows a supershell formed by an impact. This region is also characterized by disturbances in the distribution of the Hα light. The dust emission within the plane marks a thin disk that reaches the border of the optical emission. The masses associated with the dust are of the order of a few 10⁹ M_odot of gas.