Initial Conditions of Astrophysical Simulations in 3D

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Discussion Overview

The discussion centers on generating initial conditions for 3D N-body simulations in astrophysics, specifically focusing on obtaining realistic positions and velocities that resemble those found in actual galaxies. Participants explore various data sources and models that could provide more complex initial conditions beyond uniform or spherical distributions.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant mentions using explicit formulas for generating initial conditions but seeks more interesting alternatives that resemble real galaxies.
  • Another suggests the 2MASS data as a potential resource, noting that it does not provide a uniform distribution across the galaxy.
  • A different participant points to the JPL "Horizons" server for Solar System object data but expresses uncertainty about similar resources for galactic star positions.
  • One participant highlights the observational limitations of the Milky Way, stating that a complete description is unattainable due to our position within the galaxy and obscured views.
  • Another participant asserts that a 4-dimensional description is necessary for the task at hand, labeling it as an unsolved problem.

Areas of Agreement / Disagreement

Participants express a range of views on the availability and completeness of data for simulating realistic initial conditions, with no consensus on a definitive resource or method. Observational limitations and the complexity of the problem are acknowledged, indicating ongoing uncertainty.

Contextual Notes

Limitations include the lack of comprehensive data on the Milky Way due to observational constraints and the complexity of achieving a full 4-dimensional description for simulations.

jwdozer327
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So I've been playing with a little N-body code in 3D for gravitational problems and have made an OpenGL visualization to go along with it. I have been generating initial conditions (positions and velocities) using explicit formulas. I was wondering of anyone knew of any resources for getting more "interesting" initial conditions.

Right now all I generate is a uniform distribution or a spherical distribution. Is there any way to get positions and velocities for something that looks like a real galaxy or something? Does NASA have some huge CSV file for the milky way or something crazy? Google has failed me thus far. Thanks for any direction!
 
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You could try to get 2MASS data, but they don't have stars uniform over the whole galaxy.
Some model for the star and velocity distributions could be interesting, too. Take stars nearby, and assume that the whole galaxy looks similar?
 
Well, there is the JPL "Horizons" server... it gives data about Solar System objects. It's pretty funky and FTP-ish. Not very user-friendly. I don't know of anything similar for galactic positions of stars.
 
There is no complete description of the Milky Way because it is impossible to observe the entire galaxy while we are stuck within it. A large portion of the other side of the MW is obscured by the galactic core.
 
You need a 4 dimensional description to achieve what you are attempting. That remains an unsolved problem.
 

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