May 12. (EUROPE PRESS) –
Thanks to data from an enlarged and multi-imaged supernova, astronomers have successfully used a one-of-a-kind technique for measuring the expansion rate of the universe.
The work provides insight into an old debate and brings physicists closer to obtaining the most accurate measure of the age of the universe, according to its authors, led by the University of Minnesota. It is divided into two articles, published respectively in Science and The Astrophysical Journal.
In astronomy, there are two precise measurements of the expansion of the universe, also called “Hubble’s constant”. One is calculated from close-up observations of supernovae, and the second uses the “cosmic microwave background,” or radiation that began to flow freely through the universe shortly after the Big Bang.
However, these two measurements differ by about 10 percent, which has sparked extensive debate among physicists and astronomers. If both measurements are accurate, that means that scientists’ current theory of the composition of the universe is incomplete.
“If new independent measurements confirm this disagreement between the two measurements of the Hubble constant, would become a chink in the armor of our understanding of the cosmossaid Patrick Kelly, lead author of both papers and an assistant professor at the University of Minnesota School of Physics and Astronomy.
“The big question is whether there is a potential problem with one or both measurements. Our research addresses that by using an entirely different, independent way of measuring the expansion rate of the universe.”
The led team was able to calculate this value using data from a supernova discovered by Kelly in 2014, the first example of a multi-imaged supernova, which means that the telescope captured four different images of the same cosmic event. After the discovery, teams around the world predicted that the supernova would reappear in a new position in 2015, and the team at the University of Minnesota detected this additional image.
These multiple images appeared because the supernova was gravitationally captured by a cluster of galaxies, a phenomenon in which the mass of the cluster bends and magnifies the light. By using the time delays between the appearances of the 2014 and 2015 images, the researchers were able to measure the Hubble constant using a theory developed in 1964 by Norwegian astronomer Sjur Refsdal that had previously been impossible to put into practice.
The researchers’ findings don’t completely settle the debate, Kelly said, but they do provide more insight into the problem and move physicists closer to obtaining the most accurate measure of the age of the universe.
“Our measurement favors the cosmic microwave background value, although it is not in strong disagreement with the supernova value,” Kelly said. it’s a statement. “If observations of future supernovae that are also gravitationally lensing clusters yield a similar result, then it would identify a problem with the current value of the supernova or with our understanding of the dark matter of galaxy clusters.”
Using the same data, the researchers found that some current models of galaxy cluster dark matter could explain their observations of supernovae. This allowed them to determine the most accurate models for the locations of dark matter in the galaxy cluster, a question that has plagued astronomers for a long time.
