Angular dependence of coherent radio emission from magnetars with multipolar magnetic fields

Shotaro Yamasaki*, Kazlm Yavuz Ekşi, Ersin Göǧüş

*Bu çalışma için yazışmadan sorumlu yazar

Araştırma sonucu: ???type-name???Makalebilirkişi

2 Atıf (Scopus)

Özet

The recent detection of a fast radio burst (FRB) from a Galactic magnetar secured the fact that neutron stars (NSs) with superstrong magnetic fields are capable of producing these extremely bright coherent radio bursts. One of the leading mechanisms to explain the origin of such coherent radio emission is the curvature radiation process within the dipolar magnetic field structure. It has, however, already been demonstrated that magnetars likely have a more complex magnetic field topology. Here, we critically investigate curvature radio emission in the presence of inclined dipolar and quadrupolar ('quadrudipolar') magnetic fields and show that such field structures differ in their angular characteristics from a purely dipolar case. We analytically show that the shape of open field lines can be modified significantly depending on both the ratio of quadrupole to dipole field strength and their inclination angle at the NS surface. This creates multiple points along each magnetic field line that coincide with the observer's line of sight, and may explain the complex spectral and temporal structure of the observed FRBs. We also find that in quadrudipole, the radio beam can take a wider angular range and the beamwidth can be wider than that in pure dipole. This may explain why the pulse width of the transient radio pulsation from magnetars is as large as that of ordinary radio pulsars.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)3189-3194
Sayfa sayısı6
DergiMonthly Notices of the Royal Astronomical Society
Hacim512
Basın numarası3
DOI'lar
Yayın durumuYayınlandı - 1 May 2022

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Publisher Copyright:
© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.

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