The existence of a two-solar mass neutron star constrains the gravitational constant G_N at strong field

TL;DR

The paper shows that the observation of a two-solar mass neutron star constrains the gravitational constant G_N at strong fields, limiting its deviation from Earth's value to 8%, a significant improvement in testing gravity theories.

Contribution

It provides the first strong-field constraint on G_N using neutron star mass measurements combined with modern nuclear matter equations of state.

Findings

G_N cannot exceed its Earth value by more than 8% at 95% confidence.

Neutron star mass measurements can tightly constrain fundamental constants in strong gravity regimes.

This work extends tests of gravity to ten orders of magnitude higher field strengths.

Abstract

In General Relativity there is a maximum mass allowed for neutron stars that, if exceeded, entails their collapse into a black hole. Its precise value depends on details of the nuclear matter equation of state about which we are much more certain thanks to recent progress in low-energy effective theories. The discovery of a two-solar mass neutron star, near that maximum mass, when analyzed with modern equations of state, implies that Newton's gravitational constant in the star cannot exceed its value on Earth by more than 8% at 95% confidence level. This is a remarkable leap of ten orders of magnitude in the gravitational field intensity at which the constant has been constrained.