Study on the origin of the magnetic fields of magnetars and on the mechanism of the energy rekease

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(1)Thermal evolution magnetarsWe have studied the thermal evolution of magnetars taking into account the dissipation of magnetic fields. We have paid attention, especially on the influence of the magnetic field dissipation on the surface temperature. We derived the following conclusions from the comparison of the computed results with the observations of the soft gamma repeaters and anomalous X-ray pulsars.・The heat deposition due to the magnetic field dissipation should occur in the outer crust of the neutron star.・The total energy dissipated during the life time of stars should amount to 10^<49>-10^<50> erg.(2)Giant flare from SGR 1806-20On December 8 2004 the GEOTAIL satellite observed the giant flare with the huge amount of soft gamma rays from SGR 1806-20. We have calculated the X-rays and soft gamma rays emitted from the relativistic jet and have compared our model with the observations. Our numerical model can reproduce the observed light curve very well. We found the jet openin … More g angle to be less than 0.2 radian. Furthermore, compared with the isotropic model, the jet model gives 6 x 10^<46> erg to the total emitted energy, which is significantly smaller than that in the isotropic case.(3)Timing observation of 4U 0142+61We have conducted the timing analyses for the 4U 0142+61, using the ASCA data obtained in 1999. From comparing the ASCA results with the RXTE results for the timing analyses, we found that 4U 0142+61 underwent the glitch before the ASCA observation. We also obtained Δν/ν~10^<-4> and Δν^^・/ν^^・~10^<-2> for the jumps in pulse frequency and its time derivative. The fact that these values are similar to those observed in ordinary pulsars implies that the internal structure of magnetars may be similar to that of ordinary neutron stars. We have also observed the change in pulse profile, which may be associated with the glitch. We suggest that the deformation of the magnetosphere may be a cause for the pulse profile change.(4) Simultaneous observation of 4U 0142+61 in multi-wavelengthsWe have conducted the simultaneous and multi-wavelength observations in X-ray, visual and near-infrared bands. We found that the emission in the visual and near-infrared bands consists of 2 components. We also found the absorption feature in the R-band. Less