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Computing the X-Ray Universe: Overview
Incorporating both gas dynamics and mixed dark matter, a KRONOS code was
run on NCSA's 512-node Connection Machine. Each of the 512 volumes of the
simulation was assigned to a single processor node on the CM-5. The simulation, which
predicts the patterns of X-rays emitted from hot clusters of primordial
cosmic gas, the precursors of giant clusters of galaxies, was "the first [of its
kind] to be sufficiently comprehensive to make predictions that can be compared
with observations." (Mike Norman, NCSA/University of Illinois at Urbana-Champaign).
The first five movies introduce X-ray clusters and their significance to
cosmology and present the methodology underlying the simulation. A
2-dimensional simulation is portrayed to illustrate the basic mechanism of
structure formation by gravity and to introduce the notion of co-moving
coordinates in an expanding universe.
Next presented are three movies (6a, 6b, 7) depicting volumetric renderings of the simulation
volume as it is evolved forward in time by the computer, from shortly after the Big
Bang to the present. Both gas density and temperature are shown as a function of
Then, the predicted evolution of X-ray luminosity associated with formation of
hot dense gas clusters is shown (8).
Finally, you can "fly-through" the computing box to see close-ups of clusters
and get a better view of their three-dimensional structure. Gas density (and
temperature evolution) are/is presented followed by the predicted pattern of
X-ray luminosity (9, 10, 11).
Owing to the limitations of bandwidth, we are limited to offering the movies
only as "micons" and at rather low resolution. The still image shows the
predicted X ray luminosity patterns more clearly than the movies.
The Simulation "Recipe"
In addition to the gas, 50 million dark matter particles were evolved which
cluster in very much the same way as the gas. One-third of the dark matter
particles were "cold" and the remaining two-thirds were massive neutrinos
with an assumed mass of 7 electron volts. Further details, including the
calculation parameters of the simulation, can be obtained from the
and a full technical paper (postscript file) reporting this research.
- Research: Gregory Bryan, Michael Norman, NCSA/UIUC
- Additional Research: Anatoly Klypin, Christopher Loken, Jack O.Burns
- Visualization: Greg Bryan, Barry Sanders
- Post-Production: Tony Baylis, Lynn Gephart, Jay Rosenstein
- Copyright (c)1994, The Board of Trustees of the University of
to Adding Gas Dynamics Movies
Copyright, (c) 1995: Board of Trustees, University of
NCSA. Last modified, 10/18/95