CONTROVERSY OF THE GRO J1655-40 BLACK HOLE MASS AND SPIN ESTIMATES AND ITS POSSIBLE SOLUTIONS

ABSTRACT Estimates of the black hole mass M and the dimensionless spin a in the microquasar GRO J1655-40 implied by strong gravity effects related to the timing and spectral measurements are controversial, if the mass restriction determined by the dynamics related to independent optical measurements...

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Bibliographic Details
Published in:The Astrophysical journal 2016-07, Vol.825 (1), p.13-13
Main Authors: Stuchlik, Z, Kolos, M
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
BLACK HOLES
Black holes (astronomy)
Continuums
Geodesy
GRAVITATION
MASS
Mathematical models
methods: analytical
OSCILLATIONS
RESONANCE
Spectra
STARS
stars: black holes
Time measurements
X RADIATION
X-rays: individual (GRO J1655-40)
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Summary:ABSTRACT Estimates of the black hole mass M and the dimensionless spin a in the microquasar GRO J1655-40 implied by strong gravity effects related to the timing and spectral measurements are controversial, if the mass restriction determined by the dynamics related to independent optical measurements, Mopt = (5.4 0.3) M , is applied. The timing measurements of twin high-frequency (HF) quasiperiodic oscillations (QPOs) with the frequency ratio 3:2 and the simultaneously observed low-frequency (LF) QPO imply spin in the range if models based on the frequencies of geodesic epicyclic motion are used to fit the timing measurements, and the correlated creation of the twin HF QPOs and the LF QPO at a common radius is assumed. On the other hand, the spectral continuum method implies , and the Fe-line-profile method implies . This controversy can be cured if we abandon the assumption of the occurrence of the twin HF QPOs and the simultaneously observed LF QPO at a common radius. We demonstrate that the epicyclic resonance model of the twin HF QPOs is able to predict the spin in agreement with the Fe-profile method, but no model based on the geodesic epicyclic frequencies can be in agreement with the spectral continuum method. We also show that the non-geodesic string loop oscillation model of twin HF QPOs predicts spin a > 0.3 under the optical measurement limit on the black hole mass, which is in agreement with both the spectral continuum and Fe-profile methods.
ISSN:0004-637X
1538-4357
DOI:10.3847/0004-637X/825/1/13