Animation of the week - Our evolving universe
Despite their ubiquitous presence, black holes and the quasars they spawn have been absent from large-scale simulations of the universe, until now.
Carnegie Mellon University theoretical cosmologist Tiziana Di Matteo and her colleagues can now include black holes in a simulation encompassing a sizeable fraction of the universe, thanks to the resources of TeraGrid.
Perhaps one of the most exciting end products of this huge calculation is an animation showing how the universe evolved over 14 billion years.
The simulation begins before galaxies have formed, and the early frames (each frame is about half a million years) show a virtually uniform universe, corresponding well with the picture provided by cosmic microwave background studies. The first black holes appear when the universe is 300 million years old-just a child.
As the movie proceeds, matter in the universe clumps together in a filamentary fashion.
"Empty regions become emptier and emptier," says Di Matteo. Dense regions become denser, and the universe starts to look like a spider web. By the end, supermassive black holes are lurking in the center of most galaxies, quasars shine bright and then blow out, and galaxies change colors from blue to red as they age.
To obtain high-enough resolution, the team scattered 230 million hydrodynamic particles over a 33 megaparsec cube, a huge volume encompassing a million galaxies, a representative chunk of the universe. To track these particles, the simulation used 2,000 XT3 processors over four weeks of run time.
Because of the extremely high resolution, Di Matteo can zoom in at any time and watch the growth of a particular black hole.
"Ours is the first cosmological simulation to incorporate black-hole physics," says Di Matteo. "It involves more calculations than any prior similar modeling of the cosmos."
- Adapted from an article by Tim Palucka, Pittsburgh Supercomputing Center