EDP Sciences
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Volume 399, Number 2, February IV 2003
Page(s) 653 - 658
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20021774

A&A 399, 653-658 (2003)
DOI: 10.1051/0004-6361:20021774

On the precession of the isolated pulsar PSR B1828-11

A time-varying magnetic field
V. Rezania

Institute for Advanced Studies in Basic Sciences, Gava Zang, Zanjan 45195, Iran
(Received 10 September 2002 / Accepted 27 November 2002)

Analysis of both pulse timing and pulse shape variations of the isolated pulsar PSR B1828-11 shows highly correlated and strong Fourier power at periods $\simeq$1000, 500, 250, and 167 d (Stairs et al. 2000). The only description based on a free precession of the star's rigid crust coupled to the magnetic dipole torque, explains the 500 d-component, as the fundamental Fourier frequency, with its harmonic 250 d-component (Link & Epstein 2001). In this paper, we study a time-varying magnetic field model and show that if the dipole moment vector rotates with a period nearly equal to the longest (assumed fundamental) observed period ( $\simeq$1000 d) relative to the star's body axes, the resulting magnetic torque may produce the whole Fourier spectrum consistently. We also find the second and fourth harmonics at periods $\simeq$500 and 250 d are dominant for small wobble angle $\simeq$ $3^\circ$ and large field's inclination angle $\geq$ $89^\circ$. We note that, although our model simply explains the observed pulse timing and pulse shape variations of PSR B1828-11, it also evokes some serious problems with our currently understanding from the physics of the neutron star structure.

Key words: pulsar: individual: PSR B1828-11 -- stars: neutron -- stars: magnetic fields

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