Testing the Kerr Black Hole Hypothesis Using X-Ray Reflection Spectroscopy
- Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China)
- Programa de Matemática, Fundación Universitaria Konrad Lorenz, 110231 Bogotá (Colombia)
- Remeis Observatory and ECAP, Universität Erlangen-Nürnberg, D-96049 Bamberg (Germany)
We present the first X-ray reflection model for testing the assumption that the metric of astrophysical black holes is described by the Kerr solution. We employ the formalism of the transfer function proposed by Cunningham. The calculations of the reflection spectrum of a thin accretion disk are split into two parts: the calculation of the transfer function and the calculation of the local spectrum at any emission point in the disk. The transfer function only depends on the background metric and takes into account all the relativistic effects (gravitational redshift, Doppler boosting, and light bending). Our code computes the transfer function for a spacetime described by the Johannsen metric and can easily be extended to any stationary, axisymmetric, and asymptotically flat spacetime. Transfer functions and single line shapes in the Kerr metric are compared to those calculated from existing codes to check that we reach the necessary accuracy. We also simulate some observations with NuSTAR and LAD/eXTP and fit the data with our new model to show the potential capabilities of current and future observations to constrain possible deviations from the Kerr metric.
- OSTI ID:
- 22663499
- Journal Information:
- Astrophysical Journal, Vol. 842, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ACCRETION DISKS
ACCURACY
ASTROPHYSICS
AXIAL SYMMETRY
BLACK HOLES
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
EMISSION
GRAVITATION
HYPOTHESIS
KERR METRIC
RED SHIFT
REFLECTION
RELATIVISTIC RANGE
SPACE-TIME
SPECTRA
TRANSFER FUNCTIONS
VISIBLE RADIATION
X RADIATION