Multi-messenger astronomy offers new estimates of the size of neutron stars and the expansion of the universe

A combination of astrophysics measurements allowed researchers to place new constraints within a typical neutron star and provide a new calculation of the Hubble constant that indicates the rate at which the universe expands.

“We studied signals from various sources, such as recently observed neutron star fusions,” said Ingo Tews, a theorist in nuclear and particle physics, the astrophysics and cosmology group at the Los Alamos National Laboratory, who worked with a international collaboration of researchers on the analysis that will appear in the journal Science on December 18. “We analyzed gravitational wave signals and electromagnetic emissions from fusions together and combined them with previous pulsar mass measurements or recent results from NASA’s Neutron Star Composition Explorer. We find that the radius of a typical neutron star is about 11.75 kilometers and the Hubble constant is about 66.2 kilometers per second per megaparsec. “

Combining signals to gain insight into distant astrophysical phenomena is known in the art as multi-messenger astronomy. In this case, the researchers’ multi-messenger analysis allowed them to limit the uncertainty of estimating the radii of neutron stars to 800 meters.

Their new approach to measuring the Hubble constant contributes to a debate that has emerged from other competing determinations of the expansion of the universe. Measurements based on observations of exploding stars, known as supernovae, are currently at odds with those coming from the examination of the cosmic microwave background (CMB), which is essentially the remaining energy from the Big Bang. The uncertainties in the new Hubble multimessenger calculation are too great to definitively resolve the disagreement, but the measurement supports the CMB approach a little more.

Tews’ primary scientific role in the study was to provide input from the calculations of nuclear theory that represent the starting point of the analysis. His seven newspaper contributors include an international team of scientists from Germany, the Netherlands, Sweden, France and the United States.

A combination of astrophysics measurements allowed researchers to place new constraints within a typical neutron star and provide a new calculation of the Hubble constant that indicates the rate at which the universe expands.

“We studied signals from various sources, such as recently observed neutron star fusions,” said Ingo Tews, a theorist in the group of nuclear and particle physics, astrophysics and cosmology at the Los Alamos National Laboratory. an international collaboration of researchers on the analysis that will appear in the journal Science on December 18. “We analyzed together gravitational wave signals and electromagnetic emissions from fusions and combined them with previous pulsar mass measurements or recent results from the Neutron Star Interior Composition Explorer. We find that the radius of a typical neutron star is about 11 , 75 kilometers and the Hubble constant is about 66.2 kilometers per second per megaparsec. “

Combining signals to gain insight into distant astrophysical phenomena is known in the art as multi-messenger astronomy. In this case, the researchers’ multi-messenger analysis allowed them to limit the uncertainty of estimating the radii of neutron stars to 800 meters.

Their new approach to measuring the Hubble constant contributes to a debate that has emerged from other competing determinations of the expansion of the universe. Measurements based on observations of exploding stars, known as supernovae, are currently at odds with those coming from the examination of the cosmic microwave background (CMB), which is essentially the remaining energy from the Big Bang. The uncertainties in the new Hubble multimessenger calculation are too great to definitively resolve the disagreement, but the measurement supports the CMB approach a little more.

Tews’ primary scientific role in the study was to provide input from the calculations of nuclear theory that represent the starting point of the analysis. His seven newspaper contributors include an international team of scientists from Germany, the Netherlands, Sweden, France and the United States.