A previously unknown cluster of pulsating stars at the far side of our Milky Way could indicate the presence of a hidden dwarf galaxy dominated by dark matter.
Researchers looked at near-infrared data collected by the European Southern Observatory's survey VISTA and observed about four young stars approximately 300,000 light years away, Rochester Institute of Technology reported. The stars are the most distant Cepheid variables (which are used to measure distance) that have ever been discovered in our galaxy. Evidence of the galaxy first presented itself as ripples in the Milky Way's outer disk.
"I decided to see if I could actually find the thing," said study leader Sukanya Chakrabarti, assistant professor in RIT's School of Physics and Astronomy."It was a difficult prediction to test because it was close to the plane, and therefore difficult to see in the optical. This new survey, VISTA, was able to help us to lift the veil and see these young pulsating stars."
The far-off stars are believed to be associated with the dwarf galaxy, which is most likely overrun with dark matter.
"These young stars are likely the signature of this predicted galaxy," said Chakrabarti. "They can't be part of our galaxy because the disk of the Milky Way terminates at 48,000 light years."
The invisible particles known as dark matter make up about 23 percent of the entire mass of the universe, and are still largely elusive to science.
"The discovery of the Cepheid variables shows that our method of finding the location of dark-matter dominated dwarf galaxies works," Chakrabarti said. "It may help us ultimately understand what dark matter is made up of. It also shows that Newton's theory of gravity can be used out to the farthest reaches of a galaxy, and that there is no need to modify our theory of gravity."
The findings were published in a recent edition of the Astrophysical Journal Letters.
