Magnetic flux generation and wave emissions during coalescence of magnetic islands in pair plasmas

It is shown by using a two-dimensional fully relativistic electromagnetic particle-in-cell code that the tearing instability in a current sheet of pair plasmas is caused by Landau resonances of both electrons and positrons. Strong magnetic flux can be generated during coalescence of magnetic islands in the nonlinear phase of the tearing instability. The magnetic flux produced in an O-type magnetic island is caused by the counterstreaming instability found by Kazimura et al. [Astrophys. J. Lett. 498, L183 (1998); J. Phys. Soc. Jpn. 67, 1079 (1998)]. It is also shown that charge separation with a quadrupole-like structure is generated from the localized strong magnetic flux. During the decay of the quadrupole-like charge structure as well as the magnetic flux, there appear wave emissions with high-frequency electromagnetic waves and Alfvén waves as well as Langmuir waves.