Abstract

Recently neutron star masses have been estimated to very high degree of accuracy. The accurately measured highest neutron star mass is 2.01±0.04M_⊙. This puts a strong constraint on the β-equilibrated equation of state (EoS) for neutron stars. Observed neutron star masses are also direct probes of compositions of dense matter. Novel phases of matter such as hyperons, Bose-Einstein condensates of (anti)-kaons and quarks might exist in neutron star interior. The theoretical mass-radius relationship of neutron stars including exotic forms of matter is calculated and it is shown to be compatible with massive neutron stars. Unlike neutron star masses, measurements of their radii are not accurate. The moments of inertia of pulsars could be used as a tool for the determination of neutron star radii.
On the other hand, the compositions and EoS of magnetized neutron star crusts might be probed using asteroseismology. The role of magnetized crusts on quasi periodic oscillations (QPOs) in giant flares of magnetars identified as torsional shear modes is discussed in this article.