Braking Indices and Spin Evolution: Something Is Loose Inside Neutron Stars

Braking indices are used to describe the evolution of pulsars rotation, and can offer insights into the braking mechanism that dominates the slow down. Here we discuss the main difficulties associated with measuring braking indices and the complexity of interpreting these measurements. Considering recent braking index measurements on pulsars with large and regular glitches, we comment on the significant effects that the loosely coupled superfluid inside pulsars might have on their spin evolution. Copyright © International Astronomical Union 2018.