Physicists set neutron star size limits

Avatar By Le Williams | 2 years ago

Astrophysicists at the Goethe University Frankfurt and the FIAS have now succeeded in determining the size of neutron stars to within 1 mile ( 1.5 kilometers) by using an elaborate statistical approach supported by data from the measurement of gravitational waves.

The data from the detection of gravitational waves from merging neutron stars (GW170817) make an important contribution toward solving this puzzle, according to the report.

At the end of 2017, Professor Luciano Rezzolla, Institute for Theoretical Physics at the Goethe University Frankfurt and FIAS, together with his students Elias Most and Lukas Weih already exploited this data to answer a long-standing question about the maximum mass that neutron stars can support before collapsing to a black hole.

The results were also confirmed by various other groups around the world.

The physicists selected statistical methods to determine the size of neutron stars within narrow limits. In order to set the new limits, they computed more than two billion theoretical models of neutron stars by solving the Einstein equations describing the equilibrium of these relativistic stars and combined this large dataset with the constraints coming from the GW170817 gravitational wave detection.

“An approach of this type is not unusual in theoretical physics,” says Rezzolla, adding: “By exploring the results for all possible values of the parameters, we can effectively reduce our uncertainties.”

As a result, the researchers were able to determine the radius of a typical neutron star within a range of only 1.5 km: it lies between 12 and 13.5 kilometers, a result that can be further refined by future gravitational wave detections.

“However, there is a twist to all this, as neutron stars can have twin solutions,” says Schaffner-Bielich.

While there is no definite proof for their existence, they are plausible solutions and the researchers from Frankfurt have taken this possibility into account, despite the additional complications that twin stars imply.