The nine rings of the galaxy LEDA 1313424

Abstract

The galaxy LEDA 1313424 has recently been discovered by I. Pasha et al. to have nine rings. The authors of the discovery paper interpret the rings to be the result of the passing of a smaller galaxy through the center of the LEDA galaxy 56 Myr ago. In that interpretation the outermost observed ring, which has approximately 70 kpc radius, would have traveled at 1,220 km/s, an implausibly large speed. The expected speed of the 70 kpc ring is 55 km/s in the analytic theory of collisional ring galaxies used in the discovery paper to explain the pattern of ring radii. Furthermore, the widths of the observed rings are inconsistent with the predictions of the analytic theory and the assumptions underlying the analytic theory are violated in the specific case of LEDA. As an alternative interpretation we propose that the rings of LEDA are the imprint upon baryonic matter of caustic rings of dark matter. Our proposal requires that the dark matter is axions forming a Bose-Einstein condensate.

Comments: 11 pages, 2 figures