Models of Merging Galaxies

Chris Mihos, Department of Astronomy, Case Western Reserve University

Images and animations on this page are © 1994-1999 Chris Mihos. You may download them for your own personal use, but please do not reproduce in published form (ie in print or web publications) without prior consent.  Thank you.

New movies here

Ring galaxy simulation

This is a big MPEG file -- 9 megabytes. Ask yourself again if you want to download something that big. If you are sure, here it is.

Online lecture given at the 1998 Meeting of the American Association for the Advancement of Science

Supercomputer Simulations of Merging Galaxies: Mergers, Starbursts, and Galaxy Evolution

Here are quick links to the embedded animations:

Equal Mass Merger of Two Disk Galaxies

This image shows a merger between two disk galaxies of equal mass. The galaxies approach, collide, and draw apart; energy transfer during the encounter slows their motions so that they reapproach, collide, and merge. The image is color-coded to show the rate of star formation (blue = quiescent, red = more active, white = most active) rather than the actual brightness of the galaxies due to stars. You also may download a MPEG movie (485 KB) of this simulation.

A Prograde-Retrograde Merger

This MPEG movie (621 KB) shows part of the evolution of two colliding disk galaxies -- one rotating in the direction of the encounter orbit, and the other rotating against the encounter. The galaxies are affected differently as a result of the combination of rotation and tidal effects. The blue particles in the movie represent stars in the galactic disks and are collisionless, while yellow represents gas, which can collide, shock, and dissipate energy. The effects of star formation are not shown in this movie.

More Images of Equal Mass Mergers

Satellite Galaxy Mergers

This image shows a merger between a large disk galaxy and a low-mass dwarf companion. Again, the image shows the star formation rate in the disk galaxy, color-coded as for the previous encounter. The dwarf companion contains no gas; because of this it does not form stars and so is invisible in this image. The companion's center of mass is indicated by the white circle. There also is an accompanying MPEG movie (1.1 MB) of this encounter.

More Images of Satellite Mergers

You also may read a more detailed description of these models and a technical description of the modeling techniques.

The models shown here were done largely on the Cray C90 at the San Diego Supercomputer Center.

Chris Mihos

Department of Astronomy
Case Western Reserve University
10900 Euclid Ave
Cleveland, OH 44106