Through detailed numerical simulations , we demonstrate that relativistic outflows ( Lorentz factor \Gamma \sim 7 ) of electron-positron pairs can be produced by radiative acceleration even when the flow starts from a nearly pair equilibrium state at subrelativistic temperatures .
Contrary to the expectation that pairs annihilate during an expansion stage for such low temperatures , we find that most pairs can survive for the situations obtained in our previous work .
This is because in the outflow-generating region the dynamical timescale is short enough even though the fireball is optically thick to scattering .
Several problems that should be solved to apply to actual active galactic nucleus jets are discussed .