Magnetar outburst and spin-down glitch

Abstract: The outburst and spin-down glitch of magnetars are modeled from the magnetospheric point of view. We try to discuss the following four questions: (1) Which pulsar on the period and peirod-derivative diagram are more likely to show magnetar outburst? (2) Which outburst will make the glitch that triggered the outburst to become a spin-down glitch? (3) Can we model the outburst and spin-down glitch in PSR J1119$-$6127 simultaneously? (4) Why the torque variation is delayed compared with the peak of the X-ray luminosity in 1E 1048.1$-$5937 and PSR J1119$-$6127? It is found that both the global and local twisted magnetic field will affect the radiation and timing behaviors of magnetars. Especially, the delay of torque variations may due to the combined effect of increasing twist in the j-bundle and untwisting of the global magnetosphere. A toy model is build for magnetar outburst and torque variations. It can catch the general trend of magnetar outburst: decaying flux, shrinking hot spot, and torque variations.