Once cosmological curiosities -- for years scientists weren't sure they even existed -- black holes hold a key to understanding galaxy formation and the structure of the universe.
"How black holes interact with what's around them has a large effect," said Tiziana Di Matteo, the Carnegie Mellon University physics professor who is an expert on the significance of black holes in the evolution of galaxies.
Di Matteo spoke on Friday about her groundbreaking research using supercomputers to simulate the impact of black holes and dark matter on cosmic structure at a Downtown meeting of the American Physical Society.
The cosmologist was the lead author of a paper published last year based on data she collected during a 2007 simulation using supercomputers at the Pittsburgh Supercomputing Center in Oakland. The supercomputers are linked to the National Science Foundation's TeraGrid system.
The model showed immense black holes at the center of galaxies behaving in an unexpected manner. The huge objects -- often more than 1 billion times the mass of the sun -- typically exert such powerful gravitational pull that not even light escapes, hence their name.
But the gigantic ones suck in so much matter that they emit vast amounts of energy, Di Matteo said.
"As a result of Tiziana's work, we now know that those black holes expel materials, such as gases, a tremendous distance -- 10 to 50 million light years out -- and those create changes," said Rupert Croft, a CMU physics professor.
Though scientists don't know what dark matter is, they do know from measuring gravitational fluctuations that it and an element called dark energy comprise 96 percent of the universe, Di Matteo said.
"What we can see constitutes only 4 percent of all matter," she said.
The Pittsburgh supercomputers are able to simulate scales comparable to the size of the universe, Di Matteo said. So she included the 96 percent of dark matter and energy in her calculations.
That enabled her to introduce enough complexity to the simulation that the results gave scientists the best chance yet at solving the problem of how and where galaxies formed, said Michael Levine, one of the supercomputer center's two science directors. Levine is a CMU physics professor.
"Including the effects of black holes and dark matter and energy in the models produced a structure of the visible universe as we see it now," Di Matteo said. "We can match our observations with the computer models, and there is a very tight correlation."
Understanding how black holes function in galaxy formation is crucial, said Arthur Kosowsky, a University of Pittsburgh physics and astronomy professor who has published two papers in the past two years with Di Matteo.
"It's one of the components we have the least knowledge about," Kosowsky said. "And galaxies are the most fundamental building blocks of the universe. That's why I'm interested in it."
Di Matteo's research enables other scientists like Volker Springel of the Max Planck Institute for Astrophysics in Germany to examine what might happen to the Milky Way galaxy.
"We can study how the black hole at the center of the Milky Way was made, and what will happen to it when our galaxy collides and merges with (the) Andromeda galaxy in about 5 billion years from now," Springel said.
Larger text
Smaller text
Print this article
E-mail this article
