Quarks and Compact Stars (QCS)
Oct. 20-22, 2014, KIAA at Peking University, Beijing - P. R. China


Invited Talk

Supercritical Accretion in the Evolution of Neutron Star Binaries and Its Implications

Chang-Hwan Lee

Department of Physics, Pusan National University

Abstract: Recent observations of 2 solar mass neutron stars, PSR J1614-2230 and PSR J0348+0432 in neutron star-white dwarf binaries, ruled out many neutron star equations of states with which the maximum neutron star mass becomes less than 2 solar mass. On the other hand, all well-measured neutron star masses in double neutron star binaries are still less than 1.5 solar mass. This discrepancy indicates that the neutron star masses may depend on the companion types and the evolution processes of binary progenitors. Accretion process is very important to understand the properties of neutron star and/or black hole binaries. By applying the supercritical (super-Eddington) accretion on to the black hole during the giant phase of the companion star, we found the mass-period correlation in soft X-ray transients (black hole binaries) and predicted the spin of black holes. Our predictions were supported by several black hole spin observations. In this work, we apply the supercritical accretion to the neutron star binaries and estimate the final masses of first-born neutron stars both in double neutron star and neutron star-white dwarf binaries. We suggest that $ 2 \msun$ neutron stars in neutron star-white dwarf binaries might be the result of the supercritical accretion onto the first-born neutron stars during the evolution of the binary progenitors.