Testing General Relativity with X-ray reflection spectroscopy: The Konoplya-Rezzolla-Zhidenko parametrization. (arXiv:1903.12119v3 [gr-qc] UPDATED)
<a href="http://arxiv.org/find/gr-qc/1/au:+Nampalliwar_S/0/1/0/all/0/1">Sourabh Nampalliwar</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Xin_S/0/1/0/all/0/1">Shuo Xin</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Srivastava_S/0/1/0/all/0/1">Shubham Srivastava</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Abdikamalov_A/0/1/0/all/0/1">Askar B. Abdikamalov</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Ayzenberg_D/0/1/0/all/0/1">Dimitry Ayzenberg</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Bambi_C/0/1/0/all/0/1">Cosimo Bambi</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Dauser_T/0/1/0/all/0/1">Thomas Dauser</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Garcia_J/0/1/0/all/0/1">Javier A. Garcia</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Tripathi_A/0/1/0/all/0/1">Ashutosh Tripathi</a>

X-ray reflection spectroscopy is a promising technique for testing general
relativity in the strong field regime, as it can be used to test the Kerr black
hole hypothesis. In this context, the parametrically deformed black hole
metrics proposed by Konoplya, Rezzolla & Zhidenko (Phys. Rev. D93, 064015,
2016) form an important class of non-Kerr black holes. We implement this class
of black hole metrics in textsc{relxill_nk}, which is a framework we have
developed for testing for non-Kerr black holes using X-ray reflection
spectroscopy. We perform a qualitative analysis of the effect of the leading
order strong-field deformation parameters on typical observables like the
innermost stable circular orbits and the reflection spectra. We also present
the first X-ray constraints on some of the deformation parameters of this
metric, using textit{Suzaku} data from the supermassive black hole in Ark~564,
and compare them with those obtained (or expected) from other observational
techniques like gravitational waves and black hole imaging.

X-ray reflection spectroscopy is a promising technique for testing general
relativity in the strong field regime, as it can be used to test the Kerr black
hole hypothesis. In this context, the parametrically deformed black hole
metrics proposed by Konoplya, Rezzolla & Zhidenko (Phys. Rev. D93, 064015,
2016) form an important class of non-Kerr black holes. We implement this class
of black hole metrics in textsc{relxill_nk}, which is a framework we have
developed for testing for non-Kerr black holes using X-ray reflection
spectroscopy. We perform a qualitative analysis of the effect of the leading
order strong-field deformation parameters on typical observables like the
innermost stable circular orbits and the reflection spectra. We also present
the first X-ray constraints on some of the deformation parameters of this
metric, using textit{Suzaku} data from the supermassive black hole in Ark~564,
and compare them with those obtained (or expected) from other observational
techniques like gravitational waves and black hole imaging.

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