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Adding Cold and Hot Dark Matter


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This much more advanced cosmological simulation used KRONOS-CMF (CMF = Connection Machine FORTRAN), a code specially adapted to the massively parallel architecture of the Connection Machine 5 (CM-5). The calculations were conducted in three spatial dimensions, incorporating dark matter and employing initial conditions that were constrained theoretically by "cold" dark matter and observationally by the COBE measurements of the density fluctuations in the cosmic background radiation.

The algorithms developed also used N-body techniques to model the dark matter, while baryonic gas behavior was computed in a grid system containing 256^3 cells or about 17 million cells total. To optimize performance, the entire calculation divided equally among all of the CM-5's 512 processor nodes. Such "load balancing" takes maximum advantage of the computer's massively parallel architecture.

The simulations generated structures corresponding to gigantic conglomerations of primordial gas. As the gas falls into the gravitational wells associated with the dark matter, it becomes superheated. As a result, the density and temperature profiles of the gas as simulated are closely matched.

In the next round of computations, "hot" dark matter was added to the recipe and tracked with the primordial gas, first in 256^3 cells on the Convex 3880, and then in 512^3 cells on the CM-5. High resolution "mixed matter" computations are pretty sizable and demand a lot of both compute power and memory.

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Copyright, (c) 1995: Board of Trustees, University of Illinois


David Curtis. Last modified 10/9/95.