3D configuration of external reconnection in our simulation at t = 3t₀. (a) Overview of magnetic field lines with the velocity vectors denoted by the arrows. The colors green and pink represent the positive and negative of v_x, respectively. The colors of field lines have the same meaning as in Fig. 1. (b) Zoomed-in image of the reconnection region. The green arrows indicate magnetic dips. These heated curved field lines are formed through interchange reconnection between the erupting flux rope and the overlying open fields. (c) Same region as in panel b, but with the 3D curved current sheet.