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Can Any "Invariants" Be Revealed in Quasi-periodic Phenomena Observed From Sco X-1?

Sergey Kuznetsov·Lev Titarchuk
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Abstract

Using large number of Rossi X-ray Time Explorer observations of Sco X-1 we present a detailed investigation of the transition layer (TL) and the relativistic precession (RP) models. These models predict the existence of the invariant quantities: an inclination angle delta of the magnetospheric axis with the normal to the disk for the TLM and a neutron star (NS) mass M_{NS} for the RPM. Theoretical predictions of both models are tested and their self-consistency is checked. We establish that: (1) The inferred delta angle is 5.56+/-0.09 degrees. Correlation of the delta-values with the horizontal branch oscillation (HBO) frequency is rather weak. (2) There is a strong correlation between an inferred M_{NS} and the HBO frequency in the RPM frameworks. (3) We infer M_{NS} for different assumptions regarding the relations between the HBO frequency and the nodal frequency. We find that the inferred M_{NS}=2.7+/-0.1 M_sun cannot be consistent with any EOS of NS matter. We conclude that RPM fails to describe the data while TLM seems to be compatible.

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Sergey Kuznetsov, Lev Titarchuk. 2002-04-26. Can Any "Invariants" Be Revealed in Quasi-periodic Phenomena Observed From Sco X-1?. https://doi.org/10.1086/341342

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