Formation of massive skyrmion stars

As it is well known for stiff equations of state an existence of neutron stars with masses ∼ 2M⊙ is possible. Especially interesting possibility is opened if the equation of state based on the Skyrme theory is realized in nature. This equation of state was proposed recently by Ouyed and Butler. We discuss different channels of formation of massive rapidly rotating neutron stars. We use a population synthesis code to estimate numbers of massive neutron stars on different evolutionary stages. A neutron star increases its mass by accretion from a secondary companion. Significant growth of a neutron star mass due to accretion is possible only for certain values of initial parameters of the binary. In this paper we show that significant part of massive neutron stars with M ∼ 2M⊙ can be observed as millisecond radio pulsars, as X-ray sources in pair with white dwarfs, and as accreting neutron stars with very low magnetic fields.