The gravitationally lensed Supernova (SN) Refsdal was discovered by University of Minnesota astronomer Patrick Kelly in 2014 in the field of MACS J1149.6+2223, a galaxy cluster 5 billion light-years away in the constellation of Leo. This event occurred 9.3 billion years ago, and represents the first known example of a strongly lensed supernova with multiple images. It is named after astronomer Sjur Refsdal, who created a theory in 1964 on how to measure the Hubble constant (also known as Hubble’s law), which describes that galaxies are moving away from Earth at speeds proportional to their distance, so the further they are the faster the move away from Earth. SN Refsdal is the first supernova in which this measurement theory was put into practice.
There are two precise measurements of the expansion of the Universe, or Hubble constant: calculations from nearby observations of supernovae, and using the Cosmic Microwave Background that began to steam freely shortly after the Big Bang.
However, these two measurements differ by approximately 9%, which is the point of debate on current theories about the makeup and age of the Universe.
“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,” Dr. Kelly said.
“The big question is if there is a possible issue with one or both of the measurements.”
“Our research addresses that by using an independent, completely different way to measure the expansion rate of the Universe.”
In their new research, Dr. Kelly and colleagues calculated the expansion rate of the Universe by using data from four different images of SN Refsdal in 2014.
Astronomers worldwide had correctly predicted that the supernova would appear at a new position in 2015, and the NASA/ESA Hubble Space Telescope then captured a fifth image.
These multiple images appeared because SN Refsdal was gravitationally lensed by…
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