The nine rings of the galaxy LEDA 1313424

Abstract

The galaxy LEDA 1313424 has recently been discovered to have nine rings [1]. 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. We point out several difficulties with this interpretation and propose instead that the rings of LEDA are the imprint upon baryonic matter of caustic rings of dark matter. Caustic rings of dark matter, with the pattern of radii observed in the LEDA galaxy, form if the dark matter is axions. Because they move slowly (LEDA's 70 kpc ring, for example, has speed 6.6 km/s) caustic rings of dark matter are plausible sites for the star formation observed in LEDA.