An explanation for the kHz-QPO twin peaks separation in slow and fast rotators

Pétri, Jérôme

doi:10.1051/0004-6361:200500151

Cited by 23 publications

(25 citation statements)

References 18 publications

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“…Many models have been proposed to explain the rich phenomenology of twin peak QPOs Lamb et al 1985;Miller et al 1998;Psaltis et al 1999;Wagoner 1999;Wagoner et al 2001;Kato 2001;Titarchuk & Wood 2002;Abramowicz et al 2003b,c;Rezzolla et al 2003;Kluźniak et al 2004;Pétri 2005;Zhang 2005;Bursa 2005;Török et al 2007;Kato 2007Kato , 2008Stuchlík et al 2008;Čadež et al 2008;Kostić et al 2009;Germanà et al 2009;Mukhopadhyay 2009;Stuchlík et al 2013Stuchlík et al , 2014Török et al 2016;Wang et al 2015;Stuchlík et al 2015, and several others). While any acceptable model should address both the excitation mechanism and subsequent modulation of the resulting X-ray signal as well as their overall observational properties, most of the theoretical effort has been so far devoted to the observed frequencies.…”

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confidence: 99%

Constraining Models of Twin-Peak Quasi-Periodic Oscillations With Realistic Neutron Star Equations of State

Török

Goluchová

Urbanec

et al. 2016

ApJ

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Twin-peak quasi-periodic oscillations (QPOs) are observed in the X-ray power-density spectra of several accreting low-mass neutron star (NS) binaries. In our previous work we have considered several QPO models. We have identified and explored mass-angular-momentum relations implied by individual QPO models for the atoll source 4U 1636-53. In this paper we extend our study and confront QPO models with various NS equations of state (EoS). We start with simplified calculations assuming Kerr background geometry and then present results of detailed calculations considering the influence of NS quadrupole moment (related to rotationally induced NS oblateness) assuming Hartle-Thorne spacetimes. We show that the application of concrete EoS together with a particular QPO model yields a specific mass-angular-momentum relation. However, we demonstrate that the degeneracy in mass and angular momentum can be removed when the NS spin frequency inferred from the X-ray burst observations is considered. We inspect a large set of EoS and discuss their compatibility with the considered QPO models. We conclude that when the NS spin frequency in 4U 1636-53 is close to 580Hz we can exclude 51 from 90 of the considered combinations of EoS and QPO models. We also discuss additional restrictions that may exclude even more combinations. Namely, there are 13 EOS compatible with the observed twin peak QPOs and the relativistic precession model. However, when considering the low frequency QPOs and Lense-Thirring precession, only 5 EOS are compatible with the model.

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confidence: 99%

Constraining Models of Twin-Peak Quasi-Periodic Oscillations With Realistic Neutron Star Equations of State

Török

Goluchová

Urbanec

et al. 2016

ApJ

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“…Our model is able to discriminate between slow and fast rotator as already shown in [3]. Moreover, with help on new data from a dozen rotators, we were able to constrain the average mass and moment of inertia of neutron stars.…”

Section: Discussionmentioning

confidence: 56%

“…[3] has shown that this induces some driven motion in the accretion disk due to a parametric resonance. Therefore the disk will show strong response to this drive by oscillating across the equatorial plane at some given preferred radii where the resonance condition is satisfied.…”

Section: Model and Methodsmentioning

confidence: 99%

Constraining the mass and moment of inertia of neutron star from quasi-periodic oscillations in X-ray binaries

Pétri¹

2011

Proceedings of Fast X-Ray Timing and Spectroscopy at Extreme Count Rates — PoS(HTRS 2011)

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Neutron stars are the densest objects known in the Universe. Being the final product of stellar evolution, their internal composition and structure is rather poorly constrained by measurements. We put some constraints on the mass and moment of inertia of these neutron stars based on the interpretation of quasi-periodic oscillations observed in low mass X-ray binaries (LMXBs). More specifically, we use observations of high-frequency quasi-periodic observations (HF-QPOs) to look for the average mass and moment of inertia of neutron stars. This is done by applying our parametric resonance model to discriminate between slow and fast rotators. We fit our model to data from ten LMXBs for which HF-QPOs have been seen and the spin of the enclosed accreting neutron star is known. We find an average mass M * ≈ 2.0 − 2.2 M ⊙ . The corresponding average moment of inertia is then I * ≈ 1 − 3 × 10 38 kg m 2 ≈ 0.5 − 1.5 (10 km) 2 M ⊙ .

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“…Abramowicz & Fragile 2013;Ingram & Motta 2014;Motta et al 2014;Török 2005;Török et al 2012). Many QPO models have A&A 581, A35 (2015) been proposed Lamb et al 1985;Miller et al 1998;Psaltis et al 1999;Stella & Vietri 1999;Kato 2001Kato , 2007Titarchuk & Wood 2002;Rezzolla et al 2003;Schnittman & Bertschinger 2004;Pétri 2005;Zhang 2005;Tagger & Varnière 2006;Stuchlík et al 2008;Mukhopadhyay 2009;Čadež et al 2008;Kostić et al 2009;Germanà et al 2009;Germanà 2013;Lai et al 2013;Pecháček et al 2008Pecháček et al , 2013; however, each model still faces several difficulties. Moreover, the capabilities of the present X-ray observatories (e.g.…”

Section: Introductionmentioning

confidence: 99%

Twin peak high-frequency quasi-periodic oscillations as a spectral imprint of dual oscillation modes of accretion tori

Bakala

Goluchová

Török

et al. 2015

A&A

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Context. High-frequency (millisecond) quasi-periodic oscillations (HF QPOs) are observed in the X-ray power-density spectra of several microquasars and low-mass X-ray binaries. Two distinct QPO peaks, so-called twin peak QPOs, are often detected simultaneously exhibiting their frequency ratio close or equal to 3:2. A widely discussed class of proposed QPOs models is based on oscillations of accretion toroidal structures orbiting in the close vicinity of black holes or neutron stars. Aims. Following the analytic theory and previous studies of observable spectral signatures, we aim to model the twin peak QPOs as a spectral imprint of specific dual oscillation regime defined by a combination of the lowest radial and vertical oscillation mode of slender tori. We consider the model of an optically thick slender accretion torus with constant specific angular momentum. We examined power spectra and fluorescent Kα iron line profiles for two different simulation setups with the mode frequency relations corresponding to the epicyclic resonance HF QPOs model and modified relativistic precession QPOs model. Methods. We used relativistic ray-tracing implemented in the parallel simulation code LSDplus. In the background of the Kerr spacetime geometry, we analyzed the influence of the distant observer inclination and the spin of the central compact object. Relativistic optical projection of the oscillating slender torus is illustrated by images in false colours related to the frequency shift. Results. We show that performed simulations yield power spectra with the pair of dominant peaks that correspond to the frequencies of radial and vertical oscillation modes and with the peak frequency ratio equal to the proper value 3:2 on a wide range of inclinations and spin values. We also discuss exceptional cases of a very low and very high inclination, as well as unstable high spin relativistic precession-like configurations that predict a constant frequency ratio equal to 1:2. We demonstrate a significant dependency of broadened Kα iron line profiles on the inclination of the distant observer. Conclusions. This study presents a further step towards the proper model of oscillating accretion tori producing HF QPOs. More realistic future simulations should be based on incorporating the resonant coupling of oscillation modes, the influence of torus opacity, and the pressure effects on the mode frequencies and the torus shape.

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An explanation for the kHz-QPO twin peaks separation in slow and fast rotators

Cited by 23 publications

References 18 publications

Constraining Models of Twin-Peak Quasi-Periodic Oscillations With Realistic Neutron Star Equations of State

Constraining Models of Twin-Peak Quasi-Periodic Oscillations With Realistic Neutron Star Equations of State

Constraining the mass and moment of inertia of neutron star from quasi-periodic oscillations in X-ray binaries

Twin peak high-frequency quasi-periodic oscillations as a spectral imprint of dual oscillation modes of accretion tori

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