Astrophysics

Magnetic Radio Stars

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Science  16 Mar 2012:
Vol. 335, Issue 6074, pp. 1281
DOI: 10.1126/science.335.6074.1281-c
CREDITS: NANDA REA/JEFF MICHAUD

Magnetars are rapidly spinning neutron stars that are powered by extremely strong magnetic fields. Observationally, they are characterized by x-ray outbursts and by the lack of radio emission. As such, they are widely believed to differ from radio pulsars, which have much weaker magnetic fields and are instead powered by stellar rotation. Over the past 6 years, however, a few magnetars have been observed to show transient, pulsed radio emission after their x-ray outbursts. Rea et al. compared the radio emission from these magnetars with that from radio pulsars and concluded that, despite the differences, radio-emitting magnetars might also be powered by the neutron star's rotational energy, rather than the magnetic energy. The differences in the radio properties of magnetars and radio pulsars might be explained by the differences in the geometry of their magnetic fields. The topology of the magnetic field of magnetars is more complex and is related to their x-ray activity. The knowledge of a magnetar's rotational parameters and x-ray luminosity might thus suffice to predict whether it will emit radio waves.

Astrophys. J. 748, L12 (2012).

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