This is the homepage for GIDGET, the Gravitational Instability-Dominated Galaxy Evolution Tool, suitable for evolving gravitationally unstable star-forming disks over cosmological timescales.
An old version of the code is available for download here. That version of the code was last updated March 20, 2012 - it runs the models and analysis that go along with Forbes, Krumholz, and Burkert (2012) .
The latest version, used in Forbes et al (2013), is available at Bitbucket. The version (hash) used to produce the data and figures in the paper is d73c282. To download the code from Bitbucket, follow the link and click the Clone button. This will give you the command to clone the git repository, giving you the latest version of the code, and allowing you to track any changes you make to it.
It would be a good idea to let me know you are using the code so I can send you future updates, although you can just follow the page at bitbucket.
You are free to modify the code and redistribute it under the GNU Public License.
Figure 3 from Forbes et al (2013). This is a cool way to represent the balance of terms in the continuity equation at a given radius. When the column density of gas at a given location is not changing, positive terms exactly balance negative terms, and the colored band will go from -0.5 to 0.5. Galaxies like to equilibrate from the inside out, and gravitational instability (shown in blue) is quite important in redistributing the gas and supplying fuel for star formation in the centers of high redshift galaxies.