SIMBAD references

Using a large number of Rossi X-Ray Timing Explorer observations of Scorpius X-1, we present a detailed investigation of the transition layer and relativistic precession models (TLM and RPM, respectively). These models predict the existence of the invariant quantities: an inclination angle δ 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 the following: (1) The inferred δ-value is 5°.56±0°.09. Correlation of the δ-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 ν_HBO and the nodal frequency ν_nod. We find that the inferred M_NS=2.7±0.1 M_☉ cannot be consistent with any equation of state of NS matter. We conclude that the RPM fails to describe the data while the TLM seems to be compatible.