The 2:3:6 quasi-periodic oscillation structure in GRS 1915+105 and cubic subharmonics in the context of relativistic discoseismology

Ortega‐Rodríguez, Manuel; Solís-Sánchez, Hugo; López-Barquero, Vanessa; Matamoros-Alvarado, B.; Venegas-Li, A.

doi:10.1093/mnras/stu488

Cited by 7 publications

(4 citation statements)

References 34 publications

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“…The simulations described in Paper I demonstrate that in a hydrodynamic approximation, the saturation of r-mode growth can lead to the excitation of higher-frequency, vertically unstructured inertial-acoustic waves (sometimes called p-modes, but here referred to as f-modes to differentiate them from purely acoustic oscillations). The presence of such a secondary coupling supports the idea that the non-linear interaction of multiple discoseismic oscillations might be responsible for the appearance of multiple HFQPOs in some sources (e.g., Ortega-Rodríguez et al 2014). The simulations in Paper I additionally suggest that r-modes can redistribute angular momentum locally, reshaping their own trapping regions and blurring their own frequencies over time.…”

Section: Introductionsupporting

confidence: 64%

HFQPOs and discoseismic mode excitation in eccentric, relativistic discs. II. Magnetohydrodynamic simulations

Dewberry,

Latter,

Ogilvie

et al. 2020

Preprint

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Trapped inertial oscillations (r-modes) provide a promising explanation for high-frequency quasi-periodic oscillations (HFQPOs) observed in the emission from black hole X-ray binary systems. An eccentricity (or warp) can excite r-modes to large amplitudes, but concurrently the oscillations are likely damped by magnetohydrodynamic (MHD) turbulence driven by the magnetorotational instability (MRI). We force eccentricity in global, unstratified, zero-net flux MHD simulations of relativistic accretion discs, and find that a sufficiently strong disc distortion generates trapped inertial waves despite this damping. In our simulations, eccentricities above ∼ 0.03 in the inner disc excite trapped waves. In addition to the competition between r-mode damping and driving, we observe that larger amplitude eccentric structures modify and in some cases suppress MRI turbulence. Given the variety of distortions (warps as well as eccentricities) capable of amplifying r-modes, the robustness of trapped inertial wave excitation in the face of MRI turbulence in our simulations provides support for a discoseismic explanation for HFQPOs.

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Section: Introductionsupporting

confidence: 64%

HFQPOs and discoseismic mode excitation in eccentric, relativistic discs. II. Magnetohydrodynamic simulations

Dewberry,

Latter,

Ogilvie

et al. 2020

Preprint

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“…As suggested by Ferreira (2010), this might indicate that separate but correlated mechanisms, one of which could be r-mode excitation, are responsible for each oscillation. Alternatively, simulations or a dynamical systems approach might reveal a non-linear interaction between differ-ent diskoseismic modes that could give rise to oscillations with frequencies in near-integer ratios, as was preliminarily investigated with a toy model by Ortega-Rodríguez et al (2014).…”

Section: Discussionmentioning

confidence: 99%

Quasi-periodic oscillations, trapped inertial waves, and strong toroidal magnetic fields in relativistic accretionwhen th discs

Dewberry

Latter

Ogilvie

2018

Monthly Notices of the Royal Astronomical Society

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The excitation of trapped inertial waves (r-modes) by warps and eccentricities in the inner regions of a black hole accretion disc may explain the high-frequency quasiperiodic oscillations (HFQPOs) observed in the emission of Galactic X-ray binaries. However, it has been suggested that strong vertical magnetic fields push the oscillations' trapping region toward the innermost stable circular orbit (ISCO), where conditions could be unfavourable for their excitation. This paper explores the effects of large-scale magnetic fields that exhibit both toroidal and vertical components, through local and global linear analyses. We find that a strong toroidal magnetic field can reduce the detrimental effects of a vertical field: in fact, the isolation of the trapping region from the ISCO may be restored by toroidal magnetic fields approaching thermal strengths. The toroidal field couples the r-modes to the disc's magneto-acoustic response and inflates the effective pressure within the oscillations. As a consequence, the restoring force associated with the vertical magnetic field's tension is reduced. Given the analytical and numerical evidence that accretion discs threaded by poloidal magnetic field lines develop a strong toroidal component, our result provides further evidence that the detrimental effects of magnetic fields on trapped inertial modes are not as great as previously thought.

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“…The MHR equations thus introduce correlations in the output over time scales longer than the one of fluctuations and originate a red noise PDS. The idea of considering a non-linear ODE for describing some properties of accretion disc oscillations was already adopted by other authors: for instance, Ortega-Rodríguez et al (2014) considered the harmonic oscillator equation including quadratic and cubic terms and a sinusoidal forcing for describing the spectral structure of the normal mode oscillations in a thin accretion discs.…”

Section: Summary and Discussionmentioning

confidence: 99%

A non-linear mathematical model for the X-ray variability classes of the microquasar GRS 1915+105 – I. Quiescent, spiking states, and quasi-periodic oscillations

Massaro

Capitanio

Feroci

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The microquasar GRS 1915+105 is known to exhibit a very variable X-ray emission on different time-scales and patterns. We propose a system of two ordinary differential equations, adapted from the Hindmarsh–Rose model, with two dynamical variables x(t), y(t), and an input constant parameter J0, to which we added a random white noise, whose solutions for the x(t) variable reproduce consistently the X-ray light curves of several variability classes as well as the development of low-frequency quasi-periodic oscillations (QPO). We show that changing only the value of J0, the system moves from stable to unstable solutions and the resulting light curves reproduce those of the quiescent classes like ϕ and χ, the δ class and the spiking ρ class. Moreover, we found that increasing the values of J0 the system induces high-frequency oscillations that evolve into QPO when it moves into another stable region. This system of differential equations gives then a unified view of the variability of GRS 1915+105 in term of transitions between stable and unstable states driven by a single input function J0. We also present the results of a stability analysis of the equilibrium points and some considerations on the existence of periodic solutions.

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The 2:3:6 quasi-periodic oscillation structure in GRS 1915+105 and cubic subharmonics in the context of relativistic discoseismology

Cited by 7 publications

References 34 publications

HFQPOs and discoseismic mode excitation in eccentric, relativistic discs. II. Magnetohydrodynamic simulations

HFQPOs and discoseismic mode excitation in eccentric, relativistic discs. II. Magnetohydrodynamic simulations

Quasi-periodic oscillations, trapped inertial waves, and strong toroidal magnetic fields in relativistic accretionwhen th discs

A non-linear mathematical model for the X-ray variability classes of the microquasar GRS 1915+105 – I. Quiescent, spiking states, and quasi-periodic oscillations

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