Testing Ghasemi-Nodehi–Bambi spacetime with continuum-fitting method
Abstract The continuum-fitting method is the analysis of the thermal spectrum of the geometrically thin and optically thick accretion disk around stellar-mass black holes. A parametrization aiming to test the Kerr nature of astrophysical black holes was proposed in Ghasemi-Nodehi and Bambi in EPJC 7...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2020-05-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | http://link.springer.com/article/10.1140/epjc/s10052-020-7916-8 |
| Summary: | Abstract The continuum-fitting method is the analysis of the thermal spectrum of the geometrically thin and optically thick accretion disk around stellar-mass black holes. A parametrization aiming to test the Kerr nature of astrophysical black holes was proposed in Ghasemi-Nodehi and Bambi in EPJC 76:290, 2016. The metric contains 11 parameters in addition to the mass and spin parameters. One can recover the Kerr case by setting all parameters to one. In this paper, I study the continuum-fitting method in a Ghasemi-Nodehi–Bambi background. I show the impact of each of the parameters on the spectra. I then employ $$\chi ^2$$ χ2 studies and show that using the continuum-fitting method all parameters of Ghasemi-Nodehi–Bambi spacetime are degenerate. However, the parameter $$b_9$$ b9 can be constrained in the case of a high spin value and the Ghasemi-Nodehi–Bambi black hole as reference. This degeneracy means that the spectra of the Kerr case cannot be distinguished from spectra produced in Ghasemi-Nodehi–Bambi spacetime. This is a problem as regards measuring the spin of astrophysical black holes and constrain possible deviations from the Kerr case of General Relativity. |
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| ISSN: | 1434-6044 1434-6052 |