scholarly journals CONSTRAINING MODELS OF TWIN-PEAK QUASI-PERIODIC OSCILLATIONS WITH REALISTIC NEUTRON STAR EQUATIONS OF STATE

2016 ◽  
Vol 833 (2) ◽  
pp. 273 ◽  
Author(s):  
Gabriel Török ◽  
Kateřina Goluchová ◽  
Martin Urbanec ◽  
Eva Šrámková ◽  
Karel Adámek ◽  
...  
2012 ◽  
Vol 8 (S291) ◽  
pp. 524-526
Author(s):  
Gabriel Török ◽  
Martin Urbanec ◽  
Kateřina Goluchová ◽  
Pavel Bakala ◽  
Eva Šrámková ◽  
...  

AbstractIn a series of works - Török et al. (2010, 2012a) and Urbanec et al. (2010a) - we explored restrictions to neutron star properties that are implied by various models of twin-peak quasi-periodic oscillations. Here we sketch an attempt to confront the obtained mass–angular-momentum relations and limits on neutron star compactness with the parameters estimated by assuming various equations of state and the spin frequency of the atoll source 4U 1636-53.


2012 ◽  
Vol 8 (S290) ◽  
pp. 319-320
Author(s):  
Gabriel Török ◽  
Pavel Bakala ◽  
Eva Šrámková ◽  
Zdeněk Stuchlík ◽  
Martin Urbanec ◽  
...  

AbstractWe consider twin-peak quasi-periodic oscillations (QPOs) observed in the accreting low-mass neutron star (NS) binaries and explore restrictions to NS properties that are implied by various QPO models. For each model and each source, the consideration results in a specific relation between the NS mass M and the angular-momentum j rather than in their single preferred combination. Furthermore, the inferred restrictions on NS properties (or QPO models) are weaker for the low-frequency sources than for the high-frequency sources.


2012 ◽  
Vol 8 (S290) ◽  
pp. 317-318
Author(s):  
Zdeněk Stuchlík ◽  
Andrea Kotrlová ◽  
Gabriel Török

AbstractWe present a Resonant Switch (RS) model of twin peak high-frequency quasi-periodic oscillations (HF QPOs), assuming switch of twin oscillations at a resonant point, where frequencies of the upper and lower oscillations νU and νL become to be commensurable and the twin oscillations change from one pair of the oscillating modes (corresponding to a specific model of HF QPOs) to some other pair due to non-linear resonant phenomena. The RS model enables to determine range of allowed values of spin a and mass M of the neutron star located at the atoll source 4U 1636-53 where two resonant points are observed at frequency ratios νU : νL = 3:2, 5:4.


2014 ◽  
Vol 54 (5) ◽  
pp. 363-366
Author(s):  
Zdenek Stuchlík ◽  
Martin Urbanec ◽  
Andrea Kotrlová ◽  
Gabriel Török ◽  
Katerina Goluchová

The mass and spin estimates of the 4U 1636−53 neutron star obtained by the Resonant Switch (RS) model of high-frequency quasi-periodic oscillations (HF QPOs) are tested by a large variety of equations of state (EoS) governing the structure of neutron stars. Neutron star models are constructed under the Hartle–Thorne theory of slowly rotating neutron stars calculated using the observationally given rotational frequency<em> f</em><sub>rot</sub> = 580 Hz (or alternatively <em>f</em><sub>rot</sub> = 290 Hz) of the neutron star at 4U 1636−53. It is demonstrated that only two variants of the RS model are compatible with the parameters obtained by modelling neutron stars for the rotational frequency <em>f</em><sub>rot</sub> = 580 Hz. The variant giving the best fit with parameters M ~ 2.20M<sub>ʘ</sub> and <em>a</em> ~ 0.27 agrees with high precision with the prediction of one of the Skyrme EoS [1]. The variant giving the second best fit with parameters M ~ 2.12M<sub>ʘ</sub> and <em>a</em> ~ 0.20 agrees with lower precision with the prediction of the Gandolfi EoS [2].


2013 ◽  
Vol 23 ◽  
pp. 144-147
Author(s):  
DE-HUA WANG ◽  
LI CHEN ◽  
JING WANG

We take the data of twin kilohertz quasi-periodic oscillations (kHz QPOs) in neutron stars (NSs) published before 2011 as the samples, which include 15 Atoll sources and 8 Z sources. Then we test the correlation between the twin peak kHz QPOs, and compare with the samples. We find the power law relation between the lower-frequency (ν1) and the upper-frequency (ν2) of kHz QPOs can fit the data much better than the other models. For the Atoll (Z) sources, the best fitting coefficient and index of power law are a = 687 (720) and b =1.50 (1.83) respectively. The Chi-square per degree of freedom (χ2/d.o.f.) are 1.93 and 1.49 respectively.


2017 ◽  
Vol 473 (1) ◽  
pp. L136-L140 ◽  
Author(s):  
Gabriel Török ◽  
Kateřina Goluchová ◽  
Eva Šrámková ◽  
Jiří Horák ◽  
Pavel Bakala ◽  
...  

1998 ◽  
Vol 501 (1) ◽  
pp. L95-L99 ◽  
Author(s):  
Dimitrios Psaltis ◽  
Mariano Méndez ◽  
Rudy Wijnands ◽  
Jeroen Homan ◽  
Peter G. Jonker ◽  
...  

Universe ◽  
2020 ◽  
Vol 6 (8) ◽  
pp. 119 ◽  
Author(s):  
G. Fiorella Burgio ◽  
Isaac Vidaña

Background. We investigate possible correlations between neutron star observables and properties of atomic nuclei. In particular, we explore how the tidal deformability of a 1.4 solar mass neutron star, M1.4, and the neutron-skin thickness of 48Ca and 208Pb are related to the stellar radius and the stiffness of the symmetry energy. Methods. We examine a large set of nuclear equations of state based on phenomenological models (Skyrme, NLWM, DDM) and ab initio theoretical methods (BBG, Dirac–Brueckner, Variational, Quantum Monte Carlo). Results: We find strong correlations between tidal deformability and NS radius, whereas a weaker correlation does exist with the stiffness of the symmetry energy. Regarding the neutron-skin thickness, weak correlations appear both with the stiffness of the symmetry energy, and the radius of a M1.4. Our results show that whereas the considered EoS are compatible with the largest masses observed up to now, only five microscopic models and four Skyrme forces are simultaneously compatible with the present constraints on L and the PREX experimental data on the 208Pb neutron-skin thickness. We find that all the NLWM and DDM models and the majority of the Skyrme forces are excluded by these two experimental constraints, and that the analysis of the data collected by the NICER mission excludes most of the NLWM considered. Conclusion. The tidal deformability of a M1.4 and the neutron-skin thickness of atomic nuclei show some degree of correlation with nuclear and astrophysical observables, which however depends on the ensemble of adopted EoS.


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