Monte Carlo Simulation for the Formation of Magnetars

Anomalous X-ray pulsars and Soft Gamma-ray repeaters are young pulsars with the dim radio emission, and they have been rapidly spun-down to the range from 5 to 12 s. Many experts proposed that they are neutron stars with ultra-strong magnetic fields (ges 10¹⁴ G). From the modified spin down relation of pulsars Pdot prop P^2-n, we find that Vela pulsar would evolve into the classes of magnetars under some assumptions that pulsars lose its rotational energy only by magnetic dipole radiation and braking index is a constant. The evolution of inclination angle thetas between pulsars´ rotational and magnetic axes may be responsible for the increasing of magnetic field component. The results of Monte Carlo simulations show that a low braking index of n ~ 1.3-1.6 can easily result in the formation of magnetars.