The formation of shell galaxies similar to NGC 7600 in the cold dark matter cosmogony

TL;DR

This paper combines deep observations and cosmological simulations to explain the formation of shell structures in NGC 7600 within the cold dark matter framework, showing how accretion events produce observable shells.

Contribution

It demonstrates that shell galaxies like NGC 7600 can form naturally in the cold dark matter model through accretion of dark matter and stars, supported by both observations and simulations.

Findings

Shell structures result from accretion of dark matter and stars.

Simulations reproduce observed shell features.

NGC 7600's shells are consistent with CDM predictions.

Abstract

We present new deep observations of 'shell' structures in the halo of the nearby elliptical galaxy NGC 7600, alongside a movie of galaxy formation in a cold dark matter universe (available at http://www.virgo.dur.ac.uk/shell-galaxies). 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 NGC 7600. With the aid of the simulation we interpret NGC 7600 in the context of the CDM model.