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arXiv · 1309.3885

On the universality of I-Love-Q relations in magnetized neutron stars

Brynmor Haskell·Riccardo Ciolfi·Francesco Pannarale·Luciano Rezzolla
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Abstract

Recently, general relations among the quadrupole moment (Q), the moment of inertia (I), and the tidal deformability (Love number) of a neutron star were shown to exist. They are nearly independent of the nuclear matter equation of state and would be of great aid in extracting parameters from observed gravitational-waves and in testing general relativity. These relations, however, do not account for strong magnetic fields. We consider this problem by studying the effect of a strong magnetic field on slowly rotating relativistic neutron stars and show that, for simple magnetic field configurations that are purely poloidal or purely toroidal, the relation between Q and I is again nearly universal. However, different magnetic field geometries lead to different I-Q relations, and, in the case of a more realistic twisted-torus magnetic field configuration, the relation depends significantly on the equation of state, losing its universality. I-Love-Q relations must thus be used with very great care, since universality is lost for stars with long spin periods, i.e. P > 10 s, and strong magnetic fields, i.e. B > 10^12 G.

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Brynmor Haskell, Riccardo Ciolfi, Francesco Pannarale, Luciano Rezzolla. 2014-01-29. On the universality of I-Love-Q relations in magnetized neutron stars. https://doi.org/10.1093/mnrasl%2Fslt161

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