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arXiv · 1710.11112

Observational Signature of High Spin at the Event Horizon Telescope

Samuel E. Gralla·Alexandru Lupsasca·Andrew Strominger
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Abstract

We analytically compute the observational appearance of an isotropically emitting point source on a circular, equatorial orbit near the horizon of a rapidly spinning black hole. The primary image moves on a vertical line segment, in contrast to the primarily horizontal motion of the spinless case. Secondary images, also on the vertical line, display a rich caustic structure. If detected, this unique signature could serve as a "smoking gun" for a high-spin black hole in nature.

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Samuel E. Gralla, Alexandru Lupsasca, Andrew Strominger. 2018-04-02. Observational Signature of High Spin at the Event Horizon Telescope. https://doi.org/10.1093/mnras%2Fsty039

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