Neutron star masses: dwarfs, giants and neighbors

Nlte Modelatmospheres Form Dwarfs and Giants

Neutron Star Masses, Radii and Equation of State

We are closing in on neutron stars both observationally and theoretically. Observationally, a number of masses (M) and a few radii (R) have been measured as well as a number of other properties. Theoretically, modern equation of states (EOS) are more reliable due to precision measurements of nucleon-nucleon interactions, detailed calculations of binding energies of light nuclei and nuclear matt...

Constraints on Neutron Star Masses and Radii from Kilohertz QPOs

The frequencies of the highest-frequency kilohertz QPOs recently discovered in some sixteen neutron stars in low-mass X-ray binary systems are most likely orbital frequencies. If so, these QPOs provide tight upper bounds on the masses and radii of these neutron stars and interesting new constraints on the equation of state of neutron star matter. If the frequency of a kilohertz QPO can be estab...

Compatibility of neutron star masses and hyperon coupling constants

It is shown that the modern equations of state for neutron star matter based on microscopic calculations of symmetric and asymmetric nuclear matter are compatible with the lower bound on the maximum neutron-star mass for a certain range of hyperon coupling constants, which are constrained by the binding energies of hyperons in symmetric nuclear matter. The hyperons are included by means of the ...

Further Evidence for the Bimodal Distribution of Neutron-star Masses

We use a collection of 14 well-measured neutron-star masses to strengthen the case that a substantial fraction of these neutron stars were formed via electron-capture (e-capture) supernovae (SNe) as opposed to Fe corecollapse SNe. The e-capture SNe are characterized by lower resultant gravitational masses and smaller natal kicks, leading to lower orbital eccentricities when the e-capture SN has...