Investigating the multidrifting behaviour of subpulses in PSR J2007 + 0910 with the FAST

The multidrifting subpulse behaviours in PSR J2007 + 0910 have been studied carefully with the high sensitivity observations of the Five-hundred-meter Aperture Spherical radio Telescope (FAST) at 1250 MHz. We found that there are at least six different single emission modes in PSR J2007 + 0910 are observed, four of which show significant subpulse drifting behaviours (modes A, B, C, and D), and the remaining two (modes E₁ and E₂) show stationary subpulse structures. The subpulse drifting periods of modes A, B, C, and D are P_3,A = 8.7 ± 1.6P, P_3,B = 15.8 ± 1.2P, P_3,C = 21.6 ± 1.3P, and P_3,D = 32.3 ± 0.9P, respectively, where P represents the pulse period of this pulsar. The subpulse separation is almost the same for all modes P₂ = 6.01 ± 0.18°. Deep analysis suggests that the appearance and significant changes in the drifting period of multidrifting subpulse emission modes for a pulsar may originate from the aliasing effect. The observed non-drifting modes may be caused by the spark point move with a period ∼P₂. Our statistical analysis shows that the drift mode of this pulsar almost always switches from slower to faster drifts in the mode change. The interesting subpulse emission phenomenon of PSR J2007 + 0910 provides a unique opportunity to understand the switching mechanism of multidrift mode.