Time evolution of the normalized reconnection electric field , measured at the X point of various simulations. The velocity is given in Table 2, and B₀ = 0.11, 0.33, or 0.66 for ω_ce/ω_pe = 1, 3, or 6, respectively. Time is normalized by the ion cyclotron pulsation, but the growth rate of the collisionless relativistic tearing mode is not proportional to ω_ci (Pétri & Kirk 2007), hence the different time lags and shapes. In particular, for ω_ce/ω_pe = 6, the timescale of the plot is divided by 3. For pairs, the timescale is tω_ce/ 25.