72 research outputs found
Magnetically confined mountains on accreting neutron stars with multipole magnetic fields
Magnetically confined mountains on accreting neutron stars are candidates for
producing continuous gravitational waves. We formulate a magnetically confined
mountain on a neutron star with strong multipole magnetic fields and obtain
some sequences of numerical solutions. We find that the mass ellipticity of the
mountain increases by one order of magnitude if the neutron star has strong
multipole magnetic fields. As matter accretes on to the magnetic pole, the size
of the mountain increases and the magnetic fields are buried. If the neutron
star has a dipole magnetic field, the dipole magnetic field is buried and
transformed into multipole components. By contrast, if the neutron star has
both dipole and strong multipole magnetic fields, the multipole magnetic fields
are buried and transformed into a negative dipole component. We also calculate
magnetically confined mountains with toroidal magnetic fields and find that the
ellipticity becomes slightly smaller when the mountain has toroidal magnetic
fields. If the multipole magnetic fields are buried, they sustain the intense
toroidal magnetic field near the stellar surface, and the ratio of the toroidal
magnetic field to the poloidal magnetic field is close to 100. The hidden
strong toroidal magnetic fields are sustained by the buried multipole magnetic
fields.Comment: 13 pages, 12 figures, accepted for publication in MNRA
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