2022MNRAS.513.5861S

With the ever-increasing sensitivity and timing baselines of modern radio telescopes, a growing number of pulsars are being shown to exhibit transitions in their rotational and radio emission properties. In many of these cases, the two are correlated with pulsars assuming a unique spin-down rate ({dot}ν) for each of their specific emission states. In this work, we revisit 17 radio pulsars previously shown to exhibit spin-down rate variations. Using a Gaussian process regression (GPR) method to model the timing residuals and the evolution of the profile shape, we confirm the transitions already observed and reveal new transitions in 8 yr of extended monitoring with greater time resolution and enhanced observing bandwidth. We confirm that seven of these sources show emission-correlated {dot}ν transitions (Δ{dot}ν), and we characterize this correlation for one additional pulsar, PSR B1642-03. We demonstrate that GPR is able to reveal extremely subtle profile variations given sufficient data quality. We also corroborate the dependence of Δ{dot}ν amplitude on {dot}ν and pulsar characteristic age. Linking Δ{dot}ν to changes in the global magnetospheric charge density Δρ, we speculate that {dot}ν transitions associated with large Δρ values may be exhibiting detectable profile changes with improved data quality, in cases where they have not previously been observed.