Pitt professor’s grant could lead to knowledge on dark energy

The idea of dark energy has mystified scientists for more than a decade.

They know it exists… The idea of dark energy has mystified scientists for more than a decade.

They know it exists and that it fuels the expansion of the universe, but so far, that’s about all they know.

Physics and astronomy professor Jeffrey Newman hopes to change that. He will receive a five-year, $750,000 grant from the U.S. Department of Energy to develop a way to more accurately measure the distance to far-away galaxies, knowledge that will help scientists learn about dark energy.

“By figuring out which [galaxies are] close and which are far away, we can better probe and study the dark energy,” Newman said. This dark energy appears to make up most of the universe, but it has yet to be detected and studied.

Newman, who will use the money to pay graduate student assistants, hopes to broaden the potential of the world’s most powerful telescopes, including the Large Synoptic Survey Telescope, a 14-year project involving 23 universities, including Pitt. The LSST is being built on top of the Cerro Pachón Mountain, in Chile, and will be available for use in 2014. According to its official website, the telescope “will rapidly scan the sky, charting objects that change or move: from exploding supernovae to potentially hazardous near-Earth asteroids.”

“The LSST will record how the sky changes from night to night in a multicolor, movie-like format. The footage will allow for unprecedented study of elusive dark matter and dark energy, which has greater pull on the universe than dark matter,” according to a University news release.

Dark energy is the name given to the mysterious phenomenon scientists discovered in 1998.

“We can tell that the universe expands, and that expansion is accelerating,” Newman said. “We would expect expansion to slow, because gravity is pulling everything inward.”

“But in fact, the empty space in the universe is causing the expansion to accelerate. The empty space has some energy to it even though there’s no mass,” he said. “So dark energy is the generic name for what is causing the universe to expand.”

By studying billions of different galaxies with the LSST, Newman will help determine exactly how far away these galaxies are, and this will give scientists a better understanding of the empty spaces of dark energy.

Currently, scientists measure the distance to galaxies by breaking down light from the galaxies into 4000 wavelengths Newman said.

“The farther away a galaxy is, the farther back in time we are looking, which means we are looking at a smaller universe than the present one,” he said. “The farther you go back, the colors shift from blue to red. This is called redshifting.”

If a galaxy has a blue wavelength, then it is close. If it has a red wavelength, then it is far away.

“The more it gets redshifted, the farther away the galaxy is,” Newman said.

Therefore, using 4,000 different colors provides a highly accurate measurement, Newman said. However, scientists can only use this method to look at 100 galaxies at a time.

As a result, some scientists have tried measuring the distance to galaxies by breaking light down into only five colors.

“This allows for us to look at a million galaxies, rather than 100,” Newman said.

Newman said this method provides measurements that can be off by “a couple percent,” and that error would make it hard to define dark energy.

He will use his grant to work on a new method of measuring galaxies. Newman has developed an algorithm that he believes will help improve these measurements and keep errors below 0.5 percent, which is under the threshold for errors. His method was successful in tests using simulated data.

The professor’s algorithm and his research could possibly pinpoint the distance to millions of different galaxies, which will help other scientists study this mysterious dark energy.

Newman was one of 69 researchers nationwide to receive the grant, which is funded by stimulus money set aside for the U.S. Department of Energy’s Early Career Research program to support young scientists. Out of the 1,750 applicants, Newman is the only cosmologist to be selected.

The Department of Energy announced the grant opportunity last summer, and the applications were reviewed by Newman’s peers. Newman still doesn’t know who they were, but because of those nameless peers who felt his project was important enough to be considered part of the economic stimulus, Newman will spend the next five years pursuing this endeavor with Pitt students.