Identify the location, responsible components, and phenomenological diversity of pulsar glitches

Determine whether pulsar glitches originate predominantly in the crust, the core, or a mixed region; identify which stellar components are responsible for post-glitch recovery; and explain the observed diversity of glitch behavior across the pulsar population.

Background

The review surveys superfluid dynamics, vortex pinning and creep, and mutual friction as leading ingredients behind glitches and post-glitch relaxation, but highlights unresolved questions about where the angular-momentum reservoir resides and how different components couple on observable timescales.

Observations indicate wide variability in glitch sizes, recurrence, and recovery, suggesting multiple mechanisms or regions may be involved. The authors explicitly list these topics as major open problems.

References

Major open problems include identifying the location and nature of glitch activity (crustal, core, or mixed), determining the components responsible for post-glitch recovery, and explaining the observed diversity of glitch behavior.

— Spin effects in superfluidity, neutron matter and neutron stars  (2604.02782 - Sedrakian et al., 3 Apr 2026) in Conclusions

Without such a criterion, the physical origin of the observed diversity stays uncertain. It could reflect genuinely distinct physical regimes, or it might instead represent a continuum shaped by varying stellar parameters.

— Distinct Modes of Pulsar Glitch Activity Revealed by the Waiting-Time--Amplitude Morphology  (2608.28523 - Liu et al., 28 Aug 2026) in Section 1, Introduction

As glitch catalogs continue to grow, it will be important to track whether these Complex sources drift toward one class or the other, or whether they instead stabilize as a genuine intermediate category. This would provide a direct observational test of whether the Compact/Extended dichotomy is truly discrete or whether it reflects the endpoints of a continuum.

— Distinct Modes of Pulsar Glitch Activity Revealed by the Waiting-Time--Amplitude Morphology  (2608.28523 - Liu et al., 28 Aug 2026) in Section 4.1, Physical Interpretation of the Two Morphological Classes