2010年
Observational testability of a Kerr bound in the x-ray spectrum of black hole candidates
Classical and Quantum Gravity
- ,
- 巻
- 27
- 号
- 7
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1088/0264-9381/27/7/075003
The specific angular momentum of a Kerr black hole must not be larger than its mass. The observational confirmation of this bound which we call a Kerr bound directly suggests the existence of a black hole. In order to investigate observational testability of this bound by using the x-ray energy spectrum of black hole candidates, we calculate energy spectra for a super-spinning object (or a naked singularity) which is described by a Kerr metric but whose specific angular momentum is larger than its mass, and then compare the spectra of this object with those of a black hole. We assume an optically thick and geometrically thin disk around the super-spinning object and calculate its thermal energy spectrum seen by a distant observer by solving general relativistic radiative transfer equations including usual special and general relativistic effects, such as Doppler boosting, gravitational redshift, light bending and frame-dragging. Surprisingly, for a given black hole, we can always find its super-spinning counterpart with its spin a in the range whose observed spectrum is very similar to and practically indistinguishable from that of the black hole. As a result, we conclude that to confirm the Kerr bound we need more than the x-ray thermal spectrum of the black hole candidates. © 2010 IOP Publishing Ltd.
- ID情報
-
- DOI : 10.1088/0264-9381/27/7/075003
- ISSN : 0264-9381
- ISSN : 1361-6382
- SCOPUS ID : 77949563889