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arXiv · 1506.02627

Shadows of CPR black holes and tests of the Kerr metric

M. Ghasemi-Nodehi·Zilong Li·Cosimo Bambi
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Abstract

We study the shadow of the Cardoso-Pani-Rico (CPR) black hole for different values of the black hole spin $a_*$, the deformation parameters $ε_3^t$ and $ε_3^r$, and the viewing angle $i$. We find that the main impact of the deformation parameter $ε_3^t$ is the change of the size of the shadow, while the deformation parameter $ε_3^r$ affects the shape of its boundary. In general, it is impossible to test the Kerr metric, because the shadow of a Kerr black hole can be reproduced quite well by a black hole with non-vanishing $ε_3^t$ or $ε_3^r$. Deviations from the Kerr geometry could be constrained in the presence of high quality data and in the favorable case of a black hole with high values of $a_*$ and $i$. However, the shadows of some black holes with non-vanishing $ε_3^r$ present peculiar features and the possible detection of these shadows could unambiguously distinguish these objects from the standard Kerr black holes of general relativity.

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M. Ghasemi-Nodehi, Zilong Li, Cosimo Bambi. 2015-06-24. Shadows of CPR black holes and tests of the Kerr metric. https://doi.org/10.1140/epjc%2Fs10052-015-3539-x

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