2005A&A...434..649P

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 in different evolutionary stages. For stiff equations of state the existence of neutron stars with masses >2M_☉ is possible. An especially interesting situation occurs if the equation of state based on the Skyrme theory is realized in nature. 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 a significant part of massive neutron stars with M>2M_☉ can be observed as millisecond radio pulsars, as X-ray sources in pairs with white dwarfs, and as accreting neutron stars with very low magnetic fields.