A strong $\ddot{\hat{I}}½-\dot{\hat{I}}½$ correlation in radio pulsars with implications for torque variations

Abstract

We present an analysis of the spin-down parameters for 131 radio pulsars for which $\ddot{\hat{I}}½$ has been well determined. These pulsars have characteristic ages ranging from $10^3-10^8$ yr and spin periods in the range 0.4--30 s; nearly equal numbers of pulsars have $\ddot{\hat{I}}½>0$ as $\ddot{\hat{I}}½<0$. We find a strong correlation of $\ddot{\hat{I}}½$ with $\dot{\hat{I}}½$, {\em independent of the sign of} $\ddot{\hat{I}}½$. We suggest that this trend can be accounted for by small, stochastic deviations in the spin-down torque that are directly proportional (in magnitude) to the spin-down torque.

MNRAS, 4 pages, 2 figures. Minor editorial changes and typos corrected