[Paper Review] A unified accretion-ejection paradigm for black hole X-ray binaries. V. Low-frequency quasi-periodic oscillations

G. Marcel, F. Cangemi+7 more|arXiv (Cornell University)|May 20, 2020

Astrophysical Phenomena and Observations69 references4 citations

TL;DR

This paper proposes a unified JED-SAD accretion-ejection paradigm linking low-frequency quasi-periodic oscillations (LFQPOs) in GX 339-4 to the dynamical transition radius between an inner jet-emitting disk (JED) and an outer standard accretion disk (SAD). Using X-ray and radio data from four outbursts, it shows that Type C QPO frequencies correlate with Keplerian frequency at the JED-SAD transition radius via a scaling factor q ≈ 70–140, providing direct evidence that these QPOs probe the inner magnetized jet structure and supporting the JED-SAD model as a unifying framework for X-ray binary cycles.

ABSTRACT

We proposed that the spectral evolution of transient X-ray binaries (XrB) is due to an interplay between two flows: a standard accretion disk (SAD) in the outer parts and a jet-emitting disk (JED) in the inner parts. We showed in previous papers that the spectral evolution in X-ray and radio during the 2010-2011 outburst of GX339-4 can be recovered. We now investigate the presence of low frequency quasi-periodic oscillations (LFQPOs) during an X-ray outburst, and address the possible correlation between the frequencies of these LFQPOs and the transition radius between the two flows, rJ. We select X-ray and radio data form 3 outbursts of GX339-4. We use the method detailed in paper IV to obtain $r_J(t)$ and $\dot{m}_{in}(t)$ for each outburst to reproduce the correlated evolution of the X-ray spectra and the radio emission for 3 different activity cycles of GX339-4. We also independently search and report the detection of 7 new LFQPOs in addition to the literature. We show that the frequency of Type C QPOs can be linked to the dynamical JED-SAD transition radius rJ, rather than the radius of optically thin-thick transition. The scaling factor q such that $ν_{QPO} \simeq ν_K (r_J) / q$ is $q \simeq 70-140$, consistent during the 4 cycles and similar to previous studies. The JED-SAD hybrid disk configuration not only provides a successful paradigm allowing us to describe XrB cycles, but also matches the QPO frequencies evolution. QPOs provide an indirect way to probe the JED-SAD transition radius, where an undetermined process produces secular variability. The demonstrated relation between the transition radius links Type C QPOs to the transition between the two flows, tying it to the inner magnetized structure of the jets. This direct connection between the jets' structure and the process responsible for Type C QPOs could naturally explain their puzzling multi-wavelength behavior.

Motivation & Objective

• To investigate the origin of low-frequency quasi-periodic oscillations (LFQPOs) in black hole X-ray binaries within a unified accretion-ejection framework.
• To determine whether LFQPO frequencies correlate with the dynamical transition radius $ r_J $ between the jet-emitting disk (JED) and standard accretion disk (SAD).
• To test the robustness of the JED-SAD paradigm in explaining both spectral and timing variability across multiple outbursts of GX 339-4.
• To explore the physical connection between QPO-generating processes and the inner magnetized accretion structure, particularly jet formation.
• To provide independent observational support for the JED-SAD model through timing diagnostics, especially the behavior of Type C QPOs.

Proposed method

• Selected RXTE/PCA X-ray and ATCA radio light curves from three new outbursts of GX 339-4, plus one from a prior study, totaling four outbursts.
• Applied the JED-SAD modeling framework from prior papers to derive time-dependent parameters $ r_J(t) $ and $ \dot{m}_{\text{in}}(t) $, representing the dynamical transition radius and inner mass accretion rate.
• Used a single normalization factor $ \tilde{f}_R $ for radio flux across all outbursts, indicating constant jet radiative efficiency despite quenching in soft states.
• Performed independent power density spectrum analysis on X-ray data to detect and characterize LFQPOs, identifying seven new QPOs (three Type B, four Type C).
• Compared QPO frequencies to theoretical Keplerian and epicyclic frequencies at $ r_J $, testing the correlation with $ \nu_{\text{QPO}} \simeq \nu_K(r_J)/q $.
• Constrained the scaling factor $ q $ across all outbursts and assessed its consistency, finding $ q \simeq 133 \pm 4 $ when combining all four cycles.

Experimental results

Research questions

• RQ1 Can the frequencies of Type C low-frequency quasi-periodic oscillations (LFQPOs) be linked to the dynamical transition radius $ r_J $ between the JED and SAD in GX 339-4?
• RQ2 Does the observed correlation between QPO frequency and $ r_J $ support the JED-SAD paradigm as a unifying framework for X-ray binary cycles?
• RQ3 Is the scaling factor $ q $, relating QPO frequency to Kepler frequency at $ r_J $, consistent across multiple outbursts, and what does it imply about the underlying physics?
• RQ4 Why do Type B QPOs deviate from the $ r_J $-correlation at small radii, while Type C QPOs remain correlated, and what does this imply about their origin?
• RQ5 Can the timing behavior of QPOs provide independent evidence for the existence and properties of the inner magnetized accretion structure responsible for jet formation?

Key findings

• The study reports the detection of seven new LFQPOs—three Type B and four Type C—adding to the existing literature on QPOs in GX 339-4.
• The frequency of Type C QPOs shows a robust correlation with the Kepler frequency at the JED-SAD transition radius $ r_J $, with a scaling factor $ q \simeq 70-140 $, consistent across all four outbursts.
• The combined analysis of all four outbursts yields a consistent scaling factor $ q = 133 \pm 4 $, indicating a universal physical mechanism linking QPOs to the inner accretion structure.
• The correlation is stronger for Type C QPOs than for Type B QPOs, which diverge from the correlation at $ r_J \approx 4-5 $, suggesting different underlying mechanisms.
• The results support the JED-SAD paradigm as a unifying framework for X-ray binary spectral and timing evolution, with QPOs probing the transition region between magnetized and weakly magnetized accretion flows.
• The findings provide the first direct observational link between LFQPOs and the jet-producing inner structure, suggesting that QPOs are driven by secular instabilities at the JED-SAD interface.