Study of pulse jitter characteristics of PSR J1744-1134: Towards high precision pulsar timing with InPTA

Abstract

Variations in the shapes of individual pulses introduce a broadband noise component in pulsar times of arrival beyond what is expected from radiometer noise, referred to as the jitter noise. This noise limits the timing accuracy and, consequently, the sensitivity required for the detection of nanohertz gravitational waves using pulsar timing arrays. Accurate characterization of jitter noise, including its amplitude and frequency dependence, is therefore essential for each pulsar. In this work, we present the first detailed study of jitter noise in PSR J1744-1134 over the frequency range 300-500 MHz, using observations from the Indian Pulsar Timing Array experiment conducted with the upgraded Giant Metrewave Radio Telescope. We detect clear signatures of jitter in this pulsar through pulse-level analysis and Bayesian inference. Furthermore, we investigated the frequency dependence of the jitter noise and compared our results with earlier measurements at higher frequencies. The observed differences in jitter amplitude suggest a possible frequency evolution, highlighting the importance of low-frequency studies for improving pulsar timing precision and accuracy. We also investigated the effect of jitter on the high precision dispersion measure derived from our observations and found that jitter is not the limiting factor for DM precision achieved for this pulsar in the given observation timescale.