External authors:

• R. W. Tian ( Guizhou Normal University )
• R. S. Zhao ( Guizhou Normal University )
• H. Liu ( Guizhou Normal University )
• D. Li ( National Astronomical Observatory, CAS , China West Normal University , Zhejiang Laboratory )
• P. Wang ( Beijing Normal University , National Astronomical Observatory, CAS )
• C. H. Niu ( Central China Normal University )
• Biping Gong ( Huazhong University of Science & Technology )
• C. C. Miao ( Zhejiang Laboratory )
• X. Zhu ( Guizhou Normal University )
• H. W. Xu ( Central China Normal University )
• W. L. Li ( Guizhou Normal University )
• S. D. Wang ( Guizhou Normal University )
• Z. F. Tu ( Guizhou Normal University )
• Q. J. Zhi ( Guizhou Normal University )
• S. J. Dang ( Guizhou Normal University )
• L. H. Shang ( Guizhou Normal University )
• S. Xiao ( Guizhou Normal University )

Abstract:

We utilized archive data from the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) to analyze the single-pulse profile morphology of PSR J1935+1616 (B1933+16). The results show that PSR J1935+1616 exhibits significant micropulses as well as various changes in single-pulse profile morphology. In the FAST archive data, a total of 969 single pulses with microstructure were identified, accounting for 9.69% of the total pulse sample, with characteristic widths of 127.63-46.25+70.74 mu s. About half of these pulses display quasiperiodic micropulses, with a periodicity of 231.77 +/- 9.90 mu s. Among the 520 single pulses with quasiperiodic microstructure, 208 also exhibit quasiperiodicity in circular polarization, with a characteristic period of 244.70-21.05+45.66 mu s . The micropulse characteristic width in circular polarization is 106.52 +/- 46.14 mu s. Compared to normal pulses, the relative energy (E/<E>) of a single pulse with microstructure follows a double-Gaussian distribution, while those of normal pulses follow a single-Gaussian distribution. Based on the intensity of the leading and trailing components in the single-pulse profile morphology of PSR J1935+1616, we classified the pulses into four morphological modes (A, B, C, and D). The relative energy distribution of pulses in Mode A is significantly different from the others, following a double-Gaussian distribution, while the relative energy distributions in Modes B, C, and D follow a single-Gaussian distribution. Our study also suggests a possible correlation between micropulses and single-pulse profile morphology. Single pulses with micropulses are most likely to occur in Mode A, while their occurrence is least likely in Mode D.