Observations of magnetic deformation of magnetars

Through observations with the Suzaku and NuSTAR X-ray observatories, at least three magnetars have been found to show periodic phase modulations in their hard X-ray pulses, with a period T which is ∼104 times longer than their pulse periods. Among multiple observation of each object, T was kept cons...

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Bibliographic Details
Main Author: Makishima, Kazuo
Format: Conference Proceeding
Language:English
Subjects:
Emission
Magnetars
Moments of inertia
Neutron stars
Neutrons
Observatories
Stellar magnetic fields
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Summary:Through observations with the Suzaku and NuSTAR X-ray observatories, at least three magnetars have been found to show periodic phase modulations in their hard X-ray pulses, with a period T which is ∼104 times longer than their pulse periods. Among multiple observation of each object, T was kept constant, but the modulation amplitude varied. This effect can be interpreted as a manifestation of free precession of neutron stars that are axially deformed by ∼10−4 in terms of the moment of inertia. Further interpreting this deformation as caused by internal magnetic stress, these neutron stars are inferred to harbor intense toroidal magnetic fields reaching ∼1016 G. These observational results thus provide valuable information on the magnetars’ toroidal fields which are difficult to observe externally, and give clues to the X-ray emission mechanisms of magnetars.
ISSN:0094-243X
1551-7616
DOI:10.1063/5.0036975