Oscillations of relativistic axisymmetric tori and implications for modelling kHz-QPOs in neutron-star X-ray binaries

Abstract

We perform a global linear perturbative analysis, and investigate the oscillation properties of relativistic, non-selfgravitating tori orbiting around neutron stars in the slow rotation limit approximation. Extending the work done in Schwarzschild and Kerr backgrounds, we consider the axisymmetric oscillations of vertically integrated tori in the Hartle-Thorne spacetime. The equilibrium models are constructed by selecting a number of different non-Keplerian distributions of specific angular momentum, allowing for disc sizes $L\sim 0.5-600$ gravitational radii. Our results, obtained after solving a global eigenvalue problem to compute the xisymmetric $p$-modes, indicate that such oscillation modes could account with most observed lower (${\nu }_L$) and upper (${\nu }_U$) high frequency quasi-periodic oscillations for Sco X-1, and for some Z sources and Atoll sources with ${\nu }_{L}gtrsim500$ Hz. However, when ${\nu }_L\lesssim 500$ Hz, $p$-modes oscillations do not account for the linear relation ${\nu }_U=A{\nu }_L+B$, $B\ne 0$ between the upper and the lower high frequency quasi-periodic oscillations that are observed in neutron star low-mass X-ray binaries.

8 pages, 4 figures, matches accepted version for publication in MNRAS

References in corpus (10)

• X-ray Properties of Black-Hole Binaries
• Gravitational waves from the Papaloizou-Pringle instability in black hole-torus systems
• On the kHz QPO frequency correlations in bright neutron star X-ray binaries
• Dynamics of magnetized relativistic tori oscillating around black holes
• Influence of self-gravity on the runaway instability of black hole-torus systems
• The kilohertz quasi-periodic oscillations during the Z and atoll phases of the unique transient XTE J1701--462
• On the distribution of frequency ratios of kHz QPOs
• Quasi-Periodic Oscillations from Magnetorotational Turbulence
• On the nature of the first transient Z-source XTE J1701-462: its accretion disk structure, neutron star magnetic field strength, and hard tail
• NADA: A new code for studying self-gravitating tori around black holes

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• Models of quasi-periodic oscillations related to mass and spin of the GRO J1655-40 black hole
• Epicyclic oscillations in spinning particle motion around Kerr black hole applied in models fitting the quasi-periodic oscillations observed in quasars and microquasars
• Mass of intermediate black hole in the source M82 X-1 restricted by models of twin high-frequency quasi-periodic oscillations
• Controversy of the GRO J1655-40 black hole mass and spin estimates and its possible solutions
• Epicyclic oscillations in the Hartle-Thorne external geometry
• On the dynamics of tilted black hole-torus systems
• Effect of the toroidal magnetic field on the runaway instability of relativistic tori
• Oscillations of radiation pressure supported tori near black holes
• Observational constraints on the Kerr and its several single-parameter modified spacetimes using quasi-periodic oscillation data