Resonant radii of kHz quasi-periodic oscillations in Keplerian discs orbiting neutron stars

Z. Stuchlík; A. Kotrlová; G. Török

doi:doi:10.1051/0004-6361/201015029

Free access

Issue		A&A Volume 525, January 2011


Article Number		A82
Number of page(s)		5
Section		Stellar structure and evolution
DOI		http://dx.doi.org/10.1051/0004-6361/201015029
Published online		02 December 2010

A&A 525, A82 (2011)

Research Note

Resonant radii of kHz quasi-periodic oscillations in Keplerian discs orbiting neutron stars

Z. Stuchlík, A. Kotrlová and G. Török

Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezručovo nám. 13, 74601 Opava, Czech Republic
e-mail: zdenek.stuchlik@fpf.slu.cz; andrea.kotrlova@fpf.slu.cz, terek@volny.cz

Received: 21 May 2010
Accepted: 12 September 2010

Abstract

Exchange of dominance between twin kHz quasi-periodic oscillations (QPOs) observed in some low-mass-X-ray-binaries (LMXBs) suggests the possibility of a resonance between two oscillatory modes. We study the behaviour of the effective gravitational potential around specific resonant radii, and estimate the role of the higher-order terms governing the non-linear, anharmonic forcing. We discuss the impact it has on the mode amplitude in the linear and non–linear regimes. We also discuss a related possibility of lowering of the neutron star mass estimates from the highest observed QPO frequencies.

Key words: accretion, accretion disks / stars: neutron / X-rays: binaries

© ESO, 2010

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