Mitigating the Timing Impact of Anomalous Pulse Profile Shape Variability in PSR J1713+0747 with Gaussian Component Modeling

The North American Nanohertz Observatory for Gravitational Waves achieves submicrosecond timing precision for several millisecond pulsars in its pulsar timing array (PTA) with the objective of detecting and characterizing nanohertz gravitational waves. PSR J1713+0747 is one of the most precisely timed pulsars in the array, achieving submicrosecond timing precision. However, in 2021 April, PSR J1713+0747 underwent a sudden and unusual change in pulse shape that disrupted its timing stability. As PSR J1713+0747 is a key contributor to PTA sensitivity, variations in its pulse profile significantly affect the array’s sensitivity to nanohertz gravitational waves. We apply frequency-dependent Gaussian component models to decompose the pulse profile and track the evolution of individual components through the event. This component-level method maintains phase-connected timing across the shape-change event. At the L band, the recovered times of arrival (TOAs) have a median uncertainty of ∼0.47 μ s compared to ∼0.70 μ s for standard template matching. At 820 MHz, where profile frequency evolution is stronger, the recovered TOAs have a median uncertainty of ∼1.63 μ s compared to ∼0.67 μ s for standard template matching. The recovered TOAs achieve timing uncertainties comparable to conventional template matching while allowing data affected by profile variability to be retained in PTA gravitational-wave analyses. These results represent an initial step toward profile-domain timing methods capable of accounting for pulse profile evolution while reducing the need for additional timing model parameters.