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Gsquare
2004-Dec-09, 09:26 PM
For anyone here having a handle on pulsar dynamics could you please explain what causes pulsar magnetic dipole radiation? More specifically, is it due to the difference in angle between the pulsar rotational axis and the magnetic dipole field axis? Or is the magnetic dipole axis precessing ?Thx,
Gsquare

Normandy6644
2004-Dec-10, 02:06 AM
When a rapidly changing magnetic field of a spinning magnetic dipole has unaligned spin and dipole axes, it creates a strong electric field and emits radiation at the spin frequency - magnetic dipole radiation. So basically it is the fact that the spin and dipole axes are not aligned, i.e., the angle between the pulsar rotation axis and the magnetic dipole axis, as you said.

Gsquare
2004-Dec-14, 03:12 AM
Thanks Normandy, that's what I thought.

Also i subsequently came up with the equation for the luminosity of pulsar magnetic dipole radiation and it has a sin^2 term, indicating that the luminosity is proportional to the square of the sine of the angle between the dipole axis and axis or rotation.
G^2

-"The Works of the Lord are great, studied by all who have pleasure therein".-- Inscribed in the archway of the door to James Clerk Maxwell's Cavendish Laboratory - Cambridge

Normandy6644
2004-Dec-14, 03:36 AM
You're very welcome. Also, do you think you could send me your calculations? I'm kind of curious now.

Gsquare
2004-Dec-14, 03:54 PM
You're very welcome. Also, do you think you could send me your calculations? I'm kind of curious now.

I didn't actually derive the formula myself; I found it in The Cambridge Handbook of Scientifc Formulas.
Pulsar Magnetic Dipole Luminosiity, L, is given by:

L = {2(pi)(R^6)(B^2)(w^4)(sin^2[x])}/3(c^3)(u)

where R is radius, B is magnetic flux density at the magnetic poles, w is frequency, and the others are the usual constants.

I found interesting that L is dependent on the 4th power of the rotational frequency, w.
It may help to write it out by hand to see it better, (not having correct symbols on the post is awkward; I don't know whether * or ^ is typically used to raise to powers - I used ^ ).
G^2 8)

-"The Works of the Lord are great, studied by all who have pleasure therein".-- Inscribed in the archway of the door to James Clerk Maxwell's Cavendish Laboratory - Cambridge

--Edited for correction in B --