Nuclear-Physics Multi-Messenger Astrophysics Constraints on the Neutron-Star Equation of State: Adding NICER's PSR J0740+6620 Measurement

Understand

In the past few years, new observations of neutron stars and neutron-star mergers have provided a wealth of data that allow one to constrain the equation of state of nuclear matter at densities above nuclear saturation density.

• However, most observations were based on neutron stars with masses of about 1.4 solar masses, probing densities up to $\sim$ 3-4 times the nuclear saturation density.
• Even higher densities are probed inside massive neutron stars such as PSR J0740+6620.
• Very recently, new radio observations provided an update to the mass estimate for PSR J0740+6620 and X-ray observations by the NICER and XMM telescopes constrained its radius.