MASS-ANGULAR-MOMENTUM RELATIONS IMPLIED BY MODELS OF TWIN PEAK QUASI-PERIODIC OSCILLATIONS

@article{41403,
   author = {Török, Gabriel and Bakala, Pavel and Šrámková, Eva and Stuchlík, Zdeněk and Urbanec, Martin and Goluchová, Kateřina},
   article_location = {BRISTOL},
   article_number = {2},
   doi = {http://dx.doi.org/10.1088/0004-637X/760/2/138},
   keywords = {stars: neutron; X-rays: binaries},
   language = {eng},
   issn = {0004-637X},
   journal = {Astrophysical Journal},
   title = {MASS-ANGULAR-MOMENTUM RELATIONS IMPLIED BY MODELS OF TWIN PEAK QUASI-PERIODIC OSCILLATIONS},
   volume = {760},
   year = {2012}
}

TY  - JOUR
ID  - 41403
AU  - Török, Gabriel - Bakala, Pavel - Šrámková, Eva - Stuchlík, Zdeněk - Urbanec, Martin - Goluchová, Kateřina
PY  - 2012
TI  - MASS-ANGULAR-MOMENTUM RELATIONS IMPLIED BY MODELS OF TWIN PEAK QUASI-PERIODIC OSCILLATIONS
JF  - Astrophysical Journal
VL  - 760
IS  - 2
PB  - IOP PUBLISHING LTD
SN  - 0004637X
KW  - stars: neutron
KW  - X-rays: binaries
N2  - Twin peak quasi-periodic oscillations (QPOs) appear in the X-ray power-density spectra of several accreting low-mass neutron star (NS) binaries. Observations of the peculiar Z-source Circinus X-1 display unusually low QPO frequencies. Using these observations, we have previously considered the relativistic precession (RP) twin peak QPO model to estimate the mass of the central NS in Circinus X-1. We have shown that such an estimate results in a specific mass-angular-momentum (M-j) relation rather than a single preferred combination of M and j. Here we confront our previous results with another binary, the atoll source 4U 1636-53 that displays the twin peak QPOs at very high frequencies, and extend the consideration to various twin peak QPO models. In analogy to the RP model, we find that these imply their own specific M-j relations. We explore these relations for both sources and note differences in the chi(2) behavior that represent a dichotomy between high-and low-frequency sources. Based on the RP model, we demonstrate that this dichotomy is related to a strong variability of the model predictive power across the frequency plane. This variability naturally comes from the radial dependence of characteristic frequencies of orbital motion. As a consequence, the restrictions on the models resulting from observations of low-frequency sources are weaker than those in the case of high-frequency sources. Finally we also discuss the need for a correction to the RP model and consider the removing of M-j degeneracies, based on the twin peak QPO-independent angular momentum estimates.
ER  - 

TÖRÖK, Gabriel, Pavel BAKALA, Eva ŠRÁMKOVÁ, Zdeněk STUCHLÍK, Martin URBANEC a Kateřina GOLUCHOVÁ. MASS-ANGULAR-MOMENTUM RELATIONS IMPLIED BY MODELS OF TWIN PEAK QUASI-PERIODIC OSCILLATIONS. \textit{Astrophysical Journal}. BRISTOL: IOP PUBLISHING LTD, roč.~760, č.~2, 15 s. ISSN~0004-637X. doi:10.1088/0004-637X/760/2/138. 2012.