Australian astronomers have been able to locate the origin of a mysterious gamma ray that comes from the center of the Milky Way. One of the previous theories for the origin of the signal was that it came from dark matter.
To get to the bottom of the mystery, the team worked with a different hypothesis instead of thinking that it was dark matter.
10 Billion-Year-Old Stars
Astronomers from the Australian National University (ANU) worked on the hypothesis that this signal could be coming from thousands of rapidly spinning neutron stars called millisecond pulsars. Researchers discovered that the origin of the mysterious gamma ray signal at the center of the Milky Way is from 10 billion-year-old stars.
Millisecond pulsars that are close to Earth are known to be emitters of gamma signals. Tracking these gamma ray signals allowed astronomers to get a better sense of what was happening. Because of the distance from Earth to the center of the Milky Way, the signal that scientists are receiving may be a blend of thousands of whirling dense stars.
A gamma ray signal that seemed to be coming from dark matter was actually the emission from the thousands of whirling stars. This signal was a smoothly distributed blend, which scientists originally believed was from dark matter.
Astronomers were able to get their findings by using the Fermi Gamma-Ray Space Telescope. It is able to give scientists a clear view of a different energy range by allowing them to see the gamma-ray sky.
Scientists know that dark matter exists but know little else about its content. They believe that it is composed of Weakly Interacting Massive Particles, which they think generate gamma rays when they interact with each other.
It is also believed that dark matter makes up about 25 percent of the universe and it explains why galaxies are held together instead of flying apart as they spin. At the center of the Milky Way, there may be a large amount of dark matter. However, there are also ancient stars that make up the Galactic bulge.
Other researchers are still trying to verify or refute the findings that suggest that the gamma ray signals are being emitted by millisecond pulsars.
The study was published in Nature Astronomy.
Scientists are still trying to learn about the makeup of the universe. Only about 5 percent of the universe is made up of normal matter. Around 68 percent of the universe is made up of dark energy. One theory says that even though the universe is made up of empty space, that doesn't mean there isn't anything there. It contains energy that causes the universe to expand faster and faster.