Speaker
Description
Stochastic (i.e. the achromatic component of timing noise unrelated to interstellar propagation) and secular variations in the spin frequency $\nu$ of a rotation-powered pulsar complicate the interpretation of the measured second derivative of the spin frequency $\ddot{\nu}$, and hence the braking index, $n$, in terms of a power-law spin-down torque $\propto \nu^{n_{\rm pl}}$. Both categories of variation can lead to measurements of $\ddot{\nu}$ which yield anomalous braking indices, i.e. $\vert n \vert = \vert \nu \ddot{\nu} / \dot{\nu}^2 \vert \gg 1$, where the overdot symbolizes a derivative with respect to time. In this talk, I will discuss the following three key results. First, the combined effect of stochastic and secular deviations from pure power-law spin down on measurements of $\ddot{\nu}$ and its implications in observationally constraining $n$. Second, how the variance of $\ddot{\nu}$ (or equivalently $n$) satisfies a falsifiable, analytical result derived from first principles. We quantify said variance through analytic calculations, Monte Carlo simulations involving synthetic data from a phenomenological model, and modern Bayesian techniques. Third, how the variance of $\ddot{\nu}$ may be applied to real astronomical situations to predict or interpret the measured braking index $n$.
