5–9 Jul 2026
University of Canterbury
Pacific/Auckland timezone

Kerr black holes as circular polarizers

9 Jul 2026, 13:50
20m
Room E5 (Rātā / Engineering Core Building, University of Canterbury)

Room E5

Rātā / Engineering Core Building, University of Canterbury

63 Creyke Road, Ilam, Christchurch 8041, New Zealand
Parallel Session Talk Parallel sessions

Speaker

Dr De-Chang Dai (National Dong Hwa University)

Description

We study the retrograde second caustics of extremal Kerr black holes, where the intensity of the light beam is infinitely magnified. We find that the caustics of different polarized beams are split by as much as 10−3 rad by an external black hole for a suitable range of parameters. A lensing black hole at several lys away separates the polarized beams about 1012 m apart. This splitting is larger than the radius of the Earth. Therefore, an observer on Earth would see different circularly polarized light according to their location. The polarization will change while the detector is wandering around. Thus, the polarization of light beams can be an important quantity in retrolensing observations.

Research Area Gravity: Geometric theory

Author

Dr De-Chang Dai (National Dong Hwa University)

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