September 19, 2011
New Method Could Help Scientists Detect Dark Matter
Researchers from Princeton University and New York University have developed a method for detecting the collision of stars with a black hole that could help scientists uncover dark matter.
Postdoctoral researchers Shravan Hanasoge of Princeton's Department of Geosciences and Michael Kesden of NYU's Center for Cosmology and Particle Physics simulated the result of primordial black hole passing through a star.
Scientists believe that primordial black holes posses the properties of dark matter, which is thought to be remnants of the Big Bang.
Primordial back holes do not "swallow" stars like larger black holes, but cause noticeable vibrations of the star's surface as it passes through.
The team said their new discovery could help give scientists observable proof of dark matter and provide a better understanding of the universe's inner workings.
The authors of the paper published in the journal Physical Review Letters said that if primordial black holes are the source of dark matter, the number of stars in the Milky Way galaxy makes an encounter inevitable.
The new computer model can be used with current star-gazing techniques to offer a more precise method for detecting primordial back holes.
"If astronomers were just looking at the sun, the chances of observing a primordial black hole are not likely, but people are now looking at thousands of stars," Hanasoge said in a press release.
"There's a larger question of what constitutes dark matter, and if a primordial black hole were found it would fit all the parameters -- they have mass and force so they directly influence other objects in the universe, and they don't interact with light. Identifying one would have profound implications for our understanding of the early universe and dark matter."
When a primordial black hole crosses a star, its gravity squeezes the star and causes its surface to ripple as it snaps back into place. This reaction could help the interaction between primordial black holes and stars be detectable by stellar observatories.
"If you imagine poking a water balloon and watching the water ripple inside, that's similar to how a star's surface appears," Kesden said. "By looking at how a star's surface moves, you can figure out what's going on inside. If a black hole goes through, you can see the surface vibrate."
The team used the sun as a model to calculate the effect of a primordial black hole on a star's surface.
The researchers calculated the masses of primordial black holes, as well as the trajectory of the object through the sun.
The simulations were created by NASA's Tim Sandstorm using the Pleiades supercomputer at the agency's Ames Research Center in California.
One simulation shows the vibrations of the sun's surface as a primordial black hole as it passes through its interior. Another video portrays the result of a black hole just grazing the Sun's surface.
Marc Kamionkowski, a professor of physics and astronomy at Johns Hopkins University, said the new research serves as a toolkit for detecting primordial black holes.
"This is a clever idea that takes advantage of observations and measurements already made by solar physics," Kamionkowski said in a press release. "It's like someone calling you to say there might be a million dollars under your front doormat. If it turns out to not be true, it cost you nothing to look. In this case, there might be dark matter in the data sets astronomers already have, so why not look?"
He said that one significant aspect of the researchers' discovery is that it narrows the gap in the mass that can be detected by existing methods of looking for primordial black holes.
Kesden and Hanasoge say the technique could give more specific parameters for spotting a primordial black hole.
They found through their simulations that a primordial black hole larger than 1 sextillion grams would produce a noticeable effect on a star's surface.
"Now that we know primordial black holes can produce detectable vibrations in stars, we could try to look at a larger sample of stars than just our own sun," Kesden said in a press release.
"The Milky Way has 100 billion stars, so about 10,000 detectable events should be happening every year in our galaxy if we just knew where to look."
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