Estimation Of The Mass And The Spin Of The Neutron Star 4U 1728-34 Using Triples Of X-Ray Quasi-Periodic Oscillations
Abstract
X-ray quasi-periodic oscillations (QPOs) were reported for 19 different observations of the atoll source 4U 1728- 34. Three of them reveal triplets of QPOs: a lower and a upper kHz QPOs and a low-frequency QPO. Even though they are discernible only after averaging we assume them to be simultaneous. We apply a separate model (formula) for each of the three frequencies of the observed QPOs and compose a system which contains three algebraic equations for the three unknown parameters - the mass and the specific angular momentum of the central neutron star, and the radius of the orbit of orgin of the given triplet of QPOs, which allows us to find the numerical values of the later. Error propagation formulas are applied for the obtaining of interval estimates of the parameters of the star. This is done through implicit function differentiation. The calculations are repeated with several different models for the kHz QPOs.
Versions
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BibTeX
@misc{tasheva2026estimation,
title = {{Estimation Of The Mass And The Spin Of The Neutron Star 4U 1728-34 Using Triples Of X-Ray Quasi-Periodic Oscillations}},
author = {Radostina P. Tasheva and Ivan Z. Stefanov},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.32371},
eprint = {2610.32371},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.32371},
}
RIS
TY - UNPB
TI - Estimation Of The Mass And The Spin Of The Neutron Star 4U 1728-34 Using Triples Of X-Ray Quasi-Periodic Oscillations
AU - Radostina P. Tasheva
AU - Ivan Z. Stefanov
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.32371
UR - https://arxiv.org/abs/2610.32371
AB - X-ray quasi-periodic oscillations (QPOs) were reported for 19 different observations of the atoll source 4U 1728- 34. Three of them reveal triplets of QPOs: a lower and a upper kHz QPOs and a low-frequency QPO. Even though they are discernible only after averaging we assume them to be simultaneous. We apply a separate model (formula) for each of the three frequencies of the observed QPOs and compose a system which contains three algebraic equations for the three unknown parameters - the mass and the specific angular momentum of the central neutron star, and the radius of the orbit of orgin of the given triplet of QPOs, which allows us to find the numerical values of the later. Error propagation formulas are applied for the obtaining of interval estimates of the parameters of the star. This is done through implicit function differentiation. The calculations are repeated with several different models for the kHz QPOs.
ER -