How merging neutron stars amplify magnetic fields

Wed, 04 Nov 2026 00:00:00 +0000

Our new preprint, The kinematic Kelvin–Helmholtz instability-driven dynamo: implications for merging compact objects, is now on arXiv.

When neutron stars merge, their shear layer rolls into Kelvin–Helmholtz billows. We use high-resolution simulations and analytical models to trace how these motions amplify magnetic fields. At high Reynolds number, the models predict magnetar-strength fields on roughly 0.1 ms timescales, suggesting that global merger simulations may miss this rapid stage.

Explore the science highlight or watch the simulations.

The kinematic Kelvin–Helmholtz instability-driven dynamo: implications for merging compact objects

Wed, 04 Nov 2026 00:00:00 +0000

A rapid dynamo between merging stars

When two neutron stars meet, their shear layer rolls into Kelvin–Helmholtz billows. How do these motions build the intense magnetic fields found in merger simulations?

We follow three stages: shear winds the initial field; secondary instabilities break the billows into three-dimensional motions; and a dynamo amplifies both the fluctuating field and a mean field perpendicular to the original flow plane. At high Reynolds number, the dynamo growth rates become independent of Reynolds number.

Applied to neutron-star mergers, our models predict rapid vertical-field seeding and magnetar-strength fields as the dynamo leaves its kinematic stage on roughly 0.1 ms timescales. This suggests that global simulations may not resolve the relevant amplification regime.

Read the preprint → · Watch the simulations →

Dynamos | James R. Beattie

How merging neutron stars amplify magnetic fields

The kinematic Kelvin–Helmholtz instability-driven dynamo: implications for merging compact objects

A rapid dynamo between merging stars