Extensive population synthesis of isolated neutron stars with field decay - Astrophysics > High Energy Astrophysical Phenomena

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Abstract: We perform population synthesis studies of different types of neutron starstaking into account the magnetic field decay. For the first time, we confrontour results with observations using {\it simultaneously} the Log N - Log Sdistribution for nearby isolated neutron stars, the Log N - Log L distributionfor magnetars, and the distribution of radio pulsars in the $P$ - $\dot P$diagram. We find that our theoretical model is consistent with all sets of dataif the initial magnetic field distribution function follows a log-normal lawwith $<\log B 0-G > \sim 13.25$ and $\sigma {\log B 0}\sim 0.6$. Thetypical scenario includes about 10% of neutron stars born as magnetars,significant magnetic field decay during the first million years of a NS life.Evolutionary links between different subclasses may exist, although robustconclusions are not yet possible.We apply the obtained field distribution and the model of decay to studylong-term evolution of neuton stars till the stage of accretion from theinterstellar medium. It is shown that though the subsonic propeller stage canbe relatively long, initially highly magnetized neutron stars $B 0 > \sim10^{13}$ G reach the accretion regime within the Galactic lifetime if theirkick velocities are not too large. The fact that in previous studies made $>$10years ago, such objects were not considered results in a slight increase of theAccretor fraction in comparison with earlier conclusions. Most of the neutronstars similar to the Magnificent seven are expected to become accreting fromthe interstellar medium after few billion years of their evolution. They arethe main predecestors of accreting isolated neutron stars.

Autor: S.B. Popov SAI MSU, P.A. Boldin MEPhI, J.A. Miralles University of Alicante, J.A. Pons University of Alicante, B. Posselt Harvard

Fuente: https://arxiv.org/