http://arxiv.org/abs/2106.03520
It is known that the gravitational analogue of the Faraday rotation arises in the rotating spacetime due to the non-zero gravitomagnetic field. In this paper, we show that it also arises in the `non-rotating’ Reissner-Nordstr\”om spacetime, if it is immersed in a uniform magnetic field. The non-zero angular momentum (due to the presence of electric charge and magnetic field) of the electromagnetic field acts as the twist potential to raise the gravitational Faraday rotation in the said spacetime. The twisting can still exist even if the mass of the spacetime vanishes. In other words, the massless charged particle(s) immersed in a uniform magnetic field, able to twist the spacetime in principle, and responsible for the rotation of the plane of polarization of light. This, in fact, could have some applications in the basic physics and the analogue models of gravity. Here, we also study the effect of magnetic fields in the Kerr and Reissner-Nordstr\”om spacetimes, and derive the exact expressions for the gravitational Faraday rotation in the magnetized Kerr and Reissner-Nordstr\”om spacetimes. Considering the correction due to the magnetic field in the lowest possible order, we show that the logarithm correction of the distance of the source and observer in the gravitational Faraday rotation for the said spacetimes is an important consequence of the presence of magnetic field. From the astrophysical point of view, our result could be helpful to study the effects of (gravito-)magnetic fields on the propagation of polarized photons in the strong gravity regime of the rapidly rotating collapsed object.
C. Chakraborty
Tue, 8 Jun 21
49/86
Comments: 15 pages, no figures
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