Sunday, July 14

First-ever measurement of the universe’s expansion rate settles a controversy 2023

A University of Minnesota Twin Cities team employed a novel method to determine the universe’s expansion rate using data from a magnified, multiple-photographed supernova.

Their findings may help scientists better estimate the universe’s age and comprehend it.

Science and The Astrophysical Journal published the two publications.

Astronomy has two exact measures of the universe’s expansion, dubbed the “Hubble constant.” One uses local supernovae data, and the other uses the “cosmic microwave background,” or radiation that began freely streaming across the cosmos shortly after the Big Bang.

Physicists and astronomers have debated the 10% difference between these two readings. If both data are accurate, scientists’ universe hypothesis is inadequate.

“If new, independent measurements confirm this disagreement between the two measurements of the Hubble constant, it would become a chink in the armor of our understanding of the cosmos,” said Patrick Kelly, lead author of both papers and assistant professor of physics and astronomy at the University of Minnesota.

Is one or both measurements inaccurate? Our finding gauges the universe’s growth rate.”

The University of Minnesota-led researchers calculated this number using data from a supernova observed by Kelly in 2014—the first doubly photographed supernova, meaning the telescope caught four photographs of the same cosmic event. After the finding, teams worldwide projected that the supernova will resurface at a new place in 2015. The University of Minnesota team found this further picture.

Due to gravitational lensing by a galaxy cluster, the explosion produced numerous pictures. The researchers measured the Hubble Constant using a 1964 hypothesis by Norwegian astronomer Sjur Refsdal and the time delays between the 2014 and 2015 photos.

Kelly said the researchers’ results don’t settle the argument, but they help physicists determine the universe’s age more accurately.

“Our measurement favors the value from the cosmic microwave background, although it is not in strong disagreement with the supernova value,” Kelly added. “If observations of future supernovae that are also gravitationally lensed by clusters yield a similar result, then it would identify an issue with the current supernova value, or with our understanding of galaxy-cluster dark matter.”

Using the same data, the researchers discovered that several existing galaxy-cluster dark matter theories explained their supernovae findings. This allowed them to find the most accurate dark matter models for the galaxy cluster, a long-standing astronomical conundrum.

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