Relativistic Outflow of Electron-Positron Pair Plasma from a Wien   Equilibrium State
  We investigate a novel mechanism of bulk acceleration for relativistic jets of pure electron-positron pair plasma.We assumed that relativistically hot plasma is optically thick for Compton scattering and then pair plasma coupled dynamically to photons may establish quasi-Wien equilibria. We name such an electron-positron pair plasma the "Wien-fireball". Assuming there is a Wien-fireball, it is easy to form highly relativistic jets not only because coupled photons do not cause radiation drag effect, but also because coupled photons prevent catastrophic annihilation of pair plasma. It is found that the Wien-fireball provides a very effective mechanism to form high power jets. And the radiation of the Wien-fireball in blazars should be observed as MeV peaked emission at infinity with an order of kinetic power of jets. 
S.Iwamoto, F.Takahara