Timing of young radio pulsars – I. Timing noise, periodic modulation, and proper motion

ABSTRACT The smooth spin-down of young pulsars is perturbed by two non-deterministic phenomenon, glitches, and timing noise. Although the timing noise provides insights into nuclear and plasma physics at extreme densities, it acts as a barrier to high-precision pulsar timing experiments. An improved methodology based on the Bayesian inference is developed to simultaneously model the stochastic and deterministic parameters for a sample of 85 high-Ė radio pulsars observed for ∼10 yr with the 64-m Parkes radio telescope. Timing noise is known to be a red process and we develop a parametrization based on the red-noise amplitude (Ared) and spectral index (β). We measure the median Ared to be -10. 4^+1. 8-₁. ₇ yr3/2 and β to be -5. 2^+3. 0-₃. ₈ and show that the strength of timing noise scales proportionally to ^1| ̇|^-0. 6 0. 1, where ν is the spin frequency of the pulsar and ̇ is its spin-down rate. Finally, we measure significant braking indices for 19 pulsars and proper motions for 2 pulsars, and discuss the presence of periodic modulation in the arrival times of 5 pulsars.