On the Minimum Radius of Very Massive Neutron Stars

Sophia Han, Madappa Prakash.


Prospects of establishing the radii of massive neutron stars in PSR J1614-2230 and PSR J0740+6620 from NICER and Chandra observatories hold the potential to constrain the equation of state (EoS) of matter to densities well beyond those encountered in canonical stars of mass ∼1.4M. In this work, we investigate the relation between the radii of very massive neutron stars up to the maximum mass, Mmax, supported by dense matter EoSs. Results from models with hadronic matter are contrasted with those that include a first-order hadron-to-quark phase transition. We find that a lower bound on Mmax with an upper bound on the radius of massive pulsars serves to rule out too soft quark matter, and an upper bound on Mmax with a lower bound on the radius of massive pulsars strongly disfavors a transition into too-stiff quark matter appearing at low densities. The complementary role played by radius inferences from future gravitational wave events of inspiraling binary neutron stars is also briefly discussed.

Associated Fellows