Abstract For the first time, we reveal the distribution of whistler waves around a reconnection X-line by using the spiral CT scan technique, which is a novel technique analogous to that used in hospitals. This X-line was detected by the Magnetospheric Multiscale mission at the terrestrial magnetopause and has been widely believed to host a non-guide-field reconnection. With the help of this advanced technique, we find that (1) Whistler waves exist near the X-point and in the inflow region, but do not exist around the magnetosheath-side separatrix line; (2) generally, the whistler-wave power is strong near the X-point, medium in the magnetosheath inflow region, and weak in the magnetosphere inflow region; (3) the wave normal angle is quasi-perpendicular near the X-point, oblique in the magnetosphere inflow region, and quasi-parallel in the magnetosheath inflow region; and (4) the Poynting flux has random directions, meaning that these whistlers are generated locally. These whistler waves contribute significantly to the electron demagnetization, and therefore they may trigger the occurrence of magnetic reconnection.
Fu et al. (Wed,) studied this question.