New assessments of Hubble neutron star size and stability

A combination of astrophysical estimates has allowed scientists to impose new constraints on the radius of a normal neutron star and provide a new calculation of Hubble’s stability that shows the extent to which the universe is expanding.

Scientists obtained these results by studying signals emanating from several sources, for example, recently observed unions of neutron stars. They analyzed gravitational wave signals and electromagnetic emissions from the unions and combined them with previous mass measurements of pulsars or recent results from NASA’s Neutron Star Interior Composition Explorer.

They found that the average radius of a neutron star is around 11.75 kilometers and that the Hubble constant is around 66.2 kilometers per second per megaparsec.

Ingo Tews, a theorist in Nuclear and Particle Physics, Astrophysics and Cosmology at the Los Alamos National Laboratory, said, “Signals are a multifunctional astronomy to understand distant astrophysical wonders. In this case, the researchers’ multi-researcher study allowed them to limit the uncertainty of their estimate of neutron star radii to within 800 meters. ”

Hitting two neutron stars showing electromagnetic and gravitational wave emissions during the integration process
Hitting two neutron stars shows the scattering of electromagnetic and gravitational waves during the integration process. The combined interpretation of multiple messages allows astronomers to understand the composition within neutron stars and to reflect the properties of a subject under the most remote conditions in the universe. Credit: Tim Dietrich

In any case, this new approach to Hubble sustainability measurement contributes to a debate that has arisen from other competing decisions about global expansion. The uncertainties in the new multi-person Hubble calculation are too great for resolving the disagreement definitively, but the measure is slightly more supportive of the CMB approach.

The main scientific role of Tews in the study was to provide input from nuclear theory calculations that are the starting point of the study. His seven colleagues on the paper include an international team of scientists from Germany, the Netherlands, Sweden, France and the United States.

Magazine Information:
  1. T. Dietrich at the Universität Potsdam in Potsdam, Germany el al., “Multiple constraints on the state and stable Hubble neutron star equation,” Science (2020). DOI: 10.1126 / science.abb4317