摘要
We present new deep observations of "shell" structures in the halo of the nearby elliptical galaxy NGC7600, alongside a movie of galaxy formation in a cold dark matter (CDM) universe. The movie, based on an ab initio cosmological simulation, shows how continuous accretion of clumps of dark matter and stars creates a swath of diffuse circumgalactic structures. The disruption of a massive clump on a near-radial orbit creates a complex system of transient concentric shells which bare a striking resemblance to those of NGC7600. With the aid of the simulation we interpret NGC7600 in the context of the CDM model. © 2011. The American Astronomical Society. All rights reserved.