Gravitational radiation by magnetic field: application to millisecond magnetars. (arXiv:2001.05392v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Nazari_E/0/1/0/all/0/1">Elham Nazari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Roshan_M/0/1/0/all/0/1">Mahmood Roshan</a>

We investigate the direct effect of magnetic fields on gravitational waves.
To do so, we study the post-Newtonian energy-momentum tensor of the magnetized
fluid and the post-Newtonian expansion of the gravitational potential in the
wave zone. We show that the magnetic field appears even in the first
post-Newtonian order of the multipole moment tensor. Then, we derive an
explicit relativistic correction containing the magnetic field contribution to
the well-known quadrupole formula. As an application of this derivation, we
explicitly prove that the magnetic field of millisecond magnetars can be a
promising source of the gravitational waves. We show that this type of
gravitational wave is strong enough to be detected by the next generation of
the detectors.

We investigate the direct effect of magnetic fields on gravitational waves.
To do so, we study the post-Newtonian energy-momentum tensor of the magnetized
fluid and the post-Newtonian expansion of the gravitational potential in the
wave zone. We show that the magnetic field appears even in the first
post-Newtonian order of the multipole moment tensor. Then, we derive an
explicit relativistic correction containing the magnetic field contribution to
the well-known quadrupole formula. As an application of this derivation, we
explicitly prove that the magnetic field of millisecond magnetars can be a
promising source of the gravitational waves. We show that this type of
gravitational wave is strong enough to be detected by the next generation of
the detectors.

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