PSRDISP: A novel approach to modeling dispersive processes in single-pulsar noise analysis using epoch-wise dispersion measures

We present PSRDISP, a novel approach to modeling deterministic and stochastic dispersive processes in pulsar timing datasets using high-precision epoch-wise dispersion measure (DM) estimates, with a Gaussian Process-based approach. Unlike the conventional single-pulsar noise analysis methodology, which is applied to frequency-resolved times of arrival (ToAs) of pulses, this technique is applied to epoch-wise DMs which are derived from these ToAs. It can also be applied to wideband DMs measured simultaneously with wideband ToAs. Therefore, this framework provides a paradigm-agnostic approach to characterise single-pulsar dispersive processes. This method is expected to minimise the impact of achromatic red noise processes while characterising these dispersive effects. We substantiate the discussed technique with representative examples using simulated narrowband and wideband datasets with realistic noise injections. We found the recovery to be in close agreement with the injections, and agnostic to the estimation technique. Our method applies to pulsar timing experiments where precise, epoch-wise DM estimates are possible, such as the Indian Pulsar Timing Array. This technique can serve as a powerful diagnostic tool for validating single-pulsar noise analyses, which is crucial for precision pulsar timing experiments, such as Pulsar Timing Arrays.