Generation of electromagnetic waves and Alfven waves during coalescence ofmagnetic islands in pair plasmas

It is shown by using a 2-D fully relativistic electromagnetic particle-in-c ell (PIC) code that the tearing instability in a current sheet of pair plas mas is caused by Landau resonances of both electrons and positrons. Strong magnetic flux can be generated during coalescence of magnetic islands in th e nonlinear phase of the tearing instability. The magnetic flux produced in an O-type magnetic island is caused from the counter-streaming instability found by Kazimura et al. (1998). It is also shown that charge separation w ith a quadrupole-like structure is generated from the localized strong magn etic flux. During the decay of the quadrupole-like charge structure as well as the magnetic flux, there appear wave emission with high-frequency elect romagnetic waves and Alfven waves as well as Langmuir waves. We also show b y using a 3-D PIC code that current filaments associated with the O-type ma gnetic islands become unstable against the kink instability during the coal escence of current filaments.