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

A combination of astrophysical measurements allowed the researchers to put new constraints on the radius of a typical neutron star and provide a new calculation of the Hubble constant that indicates how fast the universe is expanding.

“We have studied signals from a variety of sources, for example recently observed neutron star fusions,” said Ingo Tews, theorist in the nuclear and particle physics, astrophysics and cosmology group at Los Alamos National Laboratory. , who worked with an international collaboration of researchers. on the analysis to appear in the journal Science December 18. “We jointly analyzed gravitational wave signals and electromagnetic emissions from fusions, and combined them with previous mass measurements of pulsars or recent results from NASA’s Inner Neutron Star Composition Explorer. let’s see 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 better understand distant astrophysical phenomena is known in the field as multi-messenger astronomy. In this case, the researchers’ multi-messenger analysis allowed them to limit the uncertainty of their estimate of the radii of neutron stars to less than 800 meters.

Their new approach to measuring the Hubble constant contributes to a debate that has arisen from other competing determinations of the expansion of the universe. Measurements based on observations of explosive stars known as supernovae are currently at odds with those derived from observation of the microwave cosmic background (CMB), which is essentially the remaining energy of the Big Bang. The uncertainties in the new Hubble multi-messenger computation are too large to resolve the disagreement definitively, but the measure is slightly more favorable to the CMB approach.

Tews’ main scientific role in the study was to provide the data for the calculations of nuclear theory which are the starting point for the analysis. His seven collaborators on paper include an international team of scientists from Germany, the Netherlands, Sweden, France and the United States.

A combination of astrophysical measurements allowed the researchers to put new constraints on the radius of a typical neutron star and provide a new calculation of the Hubble constant that indicates how fast the universe is expanding.

“We have studied signals from a variety of sources, for example recently observed neutron star fusions,” said Ingo Tews, a theorist in the Nuclear and Particle Physics, Astrophysics and Cosmology group at Los Alamos National Laboratory, who worked with an international collaboration of researchers on the analysis to be published in the journal Science on December 18. “We jointly analyzed gravitational wave signals and electromagnetic emissions from fusions, and combined them with previous mass measurements of pulsars or recent results from NASA’s Neutron Star interior composition explorer. 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 better understand distant astrophysical phenomena is known in the field as multi-messenger astronomy. In this case, the researchers’ multi-messenger analysis allowed them to limit the uncertainty of their estimate of the radii of neutron stars to less than 800 meters.

Their new approach to measuring the Hubble constant contributes to a debate that has arisen from other competing determinations of the expansion of the universe. Measurements based on observations of explosive stars known as supernovae are currently at odds with those derived from observation of the microwave cosmic background (CMB), which is essentially the remaining energy of the Big Bang. The uncertainties in the new Hubble multi-messenger computation are too large to resolve the disagreement definitively, but the measure is slightly more favorable to the CMB approach.

Tews’ main scientific role in the study was to provide the data for the calculations of nuclear theory which are the starting point for the analysis. His seven collaborators on paper include an international team of scientists from Germany, the Netherlands, Sweden, France and the United States.