Testing No-Hair Theorem by Quasi-Periodic Oscillations: the quadrupole of GRO J1655$-$40. (arXiv:2102.02232v2 [gr-qc] UPDATED)
<a href="http://arxiv.org/find/gr-qc/1/au:+Allahyari_A/0/1/0/all/0/1">Alireza Allahyari</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Shao_L/0/1/0/all/0/1">Lijing Shao</a>
We perform an observational test of no-hair theorem using quasi-periodic
oscillations within the relativistic precession model. Two well motivated
metrics we apply are Kerr-Q and Hartle-Thorne metrics in which the quadrupole
is the parameter that possibly encodes deviations from the Kerr black hole. The
expressions for the quasi-periodic frequencies are derived before comparing the
models with the observation. We encounter a degeneracy in constraining spin and
quadrupole parameters that makes it difficult to measure their values. In
particular, we here propose a novel test of no-hair theorem by adapting the
Hartle-Thorne metric. It turns out that a Kerr black hole is a good description
of the central object in GRO J1655$-$40 given the present observational
precisions.
We perform an observational test of no-hair theorem using quasi-periodic
oscillations within the relativistic precession model. Two well motivated
metrics we apply are Kerr-Q and Hartle-Thorne metrics in which the quadrupole
is the parameter that possibly encodes deviations from the Kerr black hole. The
expressions for the quasi-periodic frequencies are derived before comparing the
models with the observation. We encounter a degeneracy in constraining spin and
quadrupole parameters that makes it difficult to measure their values. In
particular, we here propose a novel test of no-hair theorem by adapting the
Hartle-Thorne metric. It turns out that a Kerr black hole is a good description
of the central object in GRO J1655$-$40 given the present observational
precisions.
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