# Braking index jumps in young pulsars

## TL;DR

This paper investigates the causes of braking index variations in young pulsars, proposing that small, permanent changes in the magnetic axis alignment explain observed phenomena, including timing irregularities and luminosity increases.

## Contribution

It introduces a unified physical explanation for braking index jumps in young pulsars based on axis counter-alignment, supported by observational evidence.

## Key findings

- Permanent changes in spin-down rate linked to axis alignment shifts
- Correlation between braking index jumps and X-ray luminosity increases
- Proposed model accounts for diverse pulsar timing behaviors

## Abstract

The departure of all measured pulsar braking indexes from the "canonical" dipole value 3 has been attributed to several causes in the past. Careful monitoring of the Crab pulsar has revealed permanent changes in the spin-down rate which are most likely the accumulation of small jumps in the angle $\alpha$ between the magnetic and spin axis. Recently, a large permanent change in the braking index of the in the "Crab twin" pulsar B0540-69 has been reported, and an analogous phenomenon seen in the high-field pulsar PSR 1846-0258 has been seen following a glitch, while another similar event (in PSR J119-6127) needs to be confirmed. We argue in this work that a common physical origin of all these observations can be attributed to the counter-alignment of the axis without serious violations of the observed features and with very modest inferred values of the hypothesized jump in the $\alpha$ angle. In addition, detected increases of the X-ray luminosities after the events are an additional ingredient for this interpretation. We argue that a component of a time-dependent torque has been identified, being an important ingredient towards a full solution of observed pulsar timing behavior which is in search of a consistent modeling.