Investigation of Profile Shifting and Subpulse Movement in PSR J0344-0901 with FAST

We report two phenomena detected in PSR J0344-0901 from two observations conducted at frequencies centered at 1.25 GHz using the Five-hundred-meter Aperture Spherical Radio Telescope. The first phenomenon manifests as the pulse emission shifting to later longitudinal phases and then gradually returning to its original location. The event lasts for about 216 pulse periods, with an average shift of about 0.degrees 7 measured at the peak of the integrated profile. Changes in the polarization position angle (PPA) are detected around the trailing edge of the profile, together with an increase in the profile width. The second phenomenon is characterized by the apparent movement of subpulses, which results in different subpulse track patterns across the profile window. For the first time in this pulsar, we identify four emission modes, each with unique subpulse movement, and determine the pattern periods for three of them. Pulse nulling was not detected. Modeling of the changes in the PPA using the rotating vector model gives an inclination angle of 75.degrees 12 +/- 3.degrees 80 and an impact parameter of -3.degrees 17 +/- 5.degrees 32 for this pulsar. We speculate that the subpulse movement may be related to the shifting of the pulse emission.