Dark energy, a mysterious invisible force believed to play a role in how the universe expands, may be growing stronger over time, according to a new study.
Dark energy, discovered 20 years ago by scientists measuring the distances to supernovas, or exploding stars, is described as an energy of empty space that never changes over space and time. Researchers believe it represents about 70 percent of the total universe.
The study published this week in the peer-reviewed British journal Nature Astronomy instead measures the distances to quasars, bright celestial objects located in the center of galaxies.
Using data from NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton observatory, researchers found the expansion rate of the universe is different from the model using supernovas.
“We observed quasars back to just a billion years after the Big Bang, and found that the universe’s expansion rate up to the present day was faster than we expected,” Guido Risalti, a study co-author from the department of physics and astronomy at the University of Florence in Italy, said in a statement. “This could mean dark energy is getting stronger as the cosmos grows older.”
Elisabeta Lusso of Durham University in the United Kingdom said because this technique for assessing dark energy is new, researchers took extra steps to make sure it was a reliable way to measure. “We showed that results from our technique match up with those from supernova measurements over the last 9 billion years, giving us confidence that our results are reliable at even earlier times,” she said.