Question

I was wondering where I can get a more or less complete set of a galaxy to test an n-body simulation (preferably two colliding galaxies with approx 300k to 1M elements).

Is it possible to extract this data from a public source like Nasa? Or does it make more sense to just generate the data?

Note: I Found the SDSS Skyserver website, but I don't think it's possible process this data to get useful initial conditions and a more or less complete galaxy.

Answer 1

The Milky Way has about 7E11 Msun, so in a simulation that breaks that up into 300K-1M elements, each element is going to represent at least 700,000 Msun's worth of material on average. One common scheme for this is called Smooth Particle Hydrodynamics, in which each 700,000 Msun chunk is treated as an object that interacts with other, similar objects, exerting pressure and gravity, exchanging matter and energy, etc. (So yes, you're definitely looking for a model.) The justification is basically "astrophysics." There's a reason everyone who works in it has a PhD. Plus comparison to obs
Try the folks over at Milky Way@Home. They are in the process of creating exactly what it sounds like you want, but they may ice you out until the project is completed and published, since this is their livelihood you're asking for. It's kind of like asking for the recipe to the Big Mac secret sauce or KFC's spices. Or maybe they will let you collaborate, if you have something constructive to contribute.

There's also this guy, who is apparently running simulations of a several tens of millions of elements on a supercomputer. Maybe he'd give you a random slice of 1% of his data points, and you could multiply the mass of each by 100, to give a lower-res dataset.