Shell Galaxies

Here you can find high-resolution versions of the movie presented in the Astrophysical Journal letter of Cooper et al. 2011, and a number of additional visualizations of the assembly of galactic stellar haloes. In that paper we describe the formation of a striking shell elliptical system in one of the six Aquarius simulations by Cooper et al. 2010. This distinctive halo morphology is observed in several nearby galaxies, such as NGC 7600. The movies provide a fully cosmological view of the complex history and dynamics of such systems, in extremely high resolution. They show how the continuous accretion of clumps of dark matter and stars creates a swath of diffuse structures in the haloes of massive elliptical galaxies. In the paper we show new deep observations of these structures and use the movie to interpret them in the context of the cold dark matter (CDM) model.

The movies are based on the Aquarius Project (a large-scale programme of the Virgo Consortium). Cooper et al. 2010 have combined these N-body simulations with a galaxy formation model and a prescription for associating stellar populations with dark matter particles. They use this to model the assembly of the stellar haloes around Milky Way-like galaxies.


1. arxiv:0809.0894: [abs, ps, hi-res pdf, pdf, other]
Title: Shell galaxies similar to NGC 7600 in the cold dark matter model
Authors: Andrew P. Cooper (1,3), David Martinez-Delgado (2), John Helly (3), Carlos S. Frenk (3) Shaun Cole (3) Ken Crawford (4) Stefano Zibbeti (5) Julio A. Carballo-Bello (6) R. Jay Gabanay (7) ((1) MPA, (2) MPIA, (3) Durham, (4) Rancho del Sol Observatory, (5) Dark Cosmology Centre / Copenhagen, (6) IAC, (7) Black Bird Observatory II)
Comments: to appear in Ap.J. Letters


This movie shows the formation of the stellar halo Aq-F-2 from the Aquarius series. Time runs from redshift z~4 to z=0. At z=0, the stellar halo is dominated by a spectacular shell system. The camera points towards its centre of the main galactic halo all times. The brightness of particles corresponds to their projected density, and their colour to their velocity dispersion.

Available Formats:

AqF2.avi [high quality, MPEG4, 146 MB, 1920x1200]
AqF2_1200.mpg [medium quality, MPEG1, 83 MB, 1920x1200]
AqF2_720.mpg [medium quality, MPEG1, 58 MB, 1152x720]
AqF2_480.mpg [medium quality, MPEG1, 45 MB, 768x480]
AqF2_360.mpg [low resolution, MPEG1, 29 MB, 576x360]

The video data is compressed using MPEG1 or h.264 (MPEG4) and has fairly high resolution, such that a fast PC and a good graphics card may be required to play the videos properly. You also need the right software. You can use the 'mplayer' program under Linux. On Windows you can use Windows Media Player and on a Mac Quicktime should work.

This movie shows the formation of another stellar halo, Aq-A-2, from the Aquarius series. This halo assembles most of its mass much earlier than Aq-F-2 and has a quieter growth history. It contains several prominent streams and is likely to be a closer analogue of the Milky Way or M31 haloes than Aq-F-2.

Available Formats:

AqA2.avi [high quality, MPEG4, 146 MB, 1920x1200]
AqA2_1200.mpg [medium quality, MPEG1, 82 MB, 1920x1200]
AqA2_720.mpg [medium quality, MPEG1, 58 MB, 1152x720]
AqA2_480.mpg [medium quality, MPEG1, 46 MB, 768x480]
AqA2_360.mpg [low resolution, MPEG1, 29 MB, 576x360]

This movie combines the evolution of Aq-A-2 and Aq-F-2 in side-by-side panels.

Available Formats:

AqA2F2.avi [high quality, MPEG4, 140 MB, 1920x1200]
AqA2F2_1200.mpg [medium quality, MPEG1, 121 MB, 1920x1200]
AqA2F2_720.mpg [medium quality, MPEG1, 58 MB, 1152x720]
AqA2F2_480.mpg [medium quality, MPEG1, 45 MB, 768x480]
AqA2F2_360.mpg [low resolution, MPEG1, 29 MB, 576x360]

Usage and Copyright

Copyright: ICC, University of Durham, July/2011
You are free to copy and show these movies for scientific presentations and other not-for-profit activities.

Please credit their use as follows:
J. Helly, A. Cooper, S. Cole and C. Frenk (ICC), based on simulation data from The Virgo consortium and software by V. Springel.

Last modified: Aug X, 2011