Anti-glitch of magnetar 1E 2259+586 in the wind braking scenario

Abstract

The anti-glitch of magnetar 1E 2259+586 is analyzed theoretically. An enhanced particle wind during the observational interval will taken away additional rotational energy of the neutron star. This will result in a net spin-down of the magnetar, i.e., an anti-glitch. In the wind braking scenario of anti-glitch, there are several predictions: (1) A radiative event will always accompany the anti-glitch, (2) Decrease/variation of braking index after anti-glitch, (3) Anti-glitch is just a period of enhanced spin-down. If there are enough timing observations, a period of enhanced spin-down is expected instead of an anti-glitch. Applications to previous timing events of SGR 1900+14, and PSR J1846-0258 are also included. It is shown that current timing events of 1E 2259+586, SGR 1900+14, and PSR J1846-0258 can be understood safely in the wind braking model. The enhanced spin-down and absence of an anti-glitch before the giant flare of SGR 1806-20 is consistent with the wind braking scenario.