Question

I'm modeling a pulsar as a rotating compact body with frequency ω(t), and magnetic dipole moment misaligned from the axis of rotation by angle χ. It's straightforward to calculate the radiative power leaving the system in the far-field limit: P∝ω⁴sin²χ (under the assumption that the spin-down rate is slow, ω˙≪ω₂).

By energy conservation, we can express the torque on the pulsar: τ∝−ω³sin²χ. My question is, through what mechanism is torque applied to the pulsar? Is the accelerating dipole moment self-interacting through the field it generates?

EDIT:

I understand this is not a realistic model for a pulsar. This is a toy model I'm using to frame my question. The radiation carries away energy and angular momentum, so the pulsar must spin-down - that is clear to me.

What I do not understand is the torque. We have a compact massive body losing angular momentum. So there exists a non-zero torque on the pulsar. What object exerts this torque?

Answer 1

The torque applied to a pulsar is due to the interaction between its magnetic dipole moment and the magnetic field it generates.

Step-by-step explanation:

The torque applied to a pulsar is due to the interaction between its magnetic dipole moment and the magnetic field it generates.

As the pulsar rotates, the misalignment of the magnetic dipole moment with the axis of rotation causes the magnetic field lines to be asymmetrical, resulting in a torque on the pulsar.

This torque is responsible for slowing down the rotation of the pulsar over time.