Single-pulse Shape Variability in Millisecond Pulsars

Wang, Shuangqiang

Pulsars usually show stochastic single-pulse profile variations intrinsic to the pulsar emission process. Understanding the jitter noise which results from the single-pulse phase and shape variations is important for the detection of gravitational waves with pulsar timing array. We present the short-term profile and timing stability of 12 bright millisecond pulsars by analyzing the single-pulse phenomenology and arrival time variability using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Single-pulses are detected in all of these pulsars because of our highly sensitive observations. The single-pulse energy follows Gaussian or log-normal distribution. Using the longitude-resolved fluctuation spectrum analysis, we find that 9 of 12 pulsars show periodical amplitude modulations. We find strong correlation between jitter noise and pulse width with the correlation coefficient of 0.85. We examine the achievable timing precision using a subselection of single-pulses with a specific range of flux density or peak intensity, and slight improvement on timing precision is achievable for some pulsars.