Kalamkar, M. and Casella, P. and Uttley, P. and O'Brien, K. and Russell, D. and Maccarone, T. and van der Klis, M. and Vincentelli, F. (2016) 'Detection of the first infra-red quasi-periodic oscillation in a black hole X-ray binary.', Monthly notices of the Royal Astronomical Society., 460 (3). pp. 3284-3291.
We present the analysis of fast variability of Very Large Telescope/ISAAC (Infrared Spectrometer And Array Camera) (infra-red), XMM–Newton/OM (optical) and EPIC-pn (X-ray), and RXTE/PCA (X-ray) observations of the black hole X-ray binary GX 339−4 in a rising hard state of its outburst in 2010. We report the first detection of a quasi-periodic oscillation (QPO) in the infra-red band (IR) of a black hole X-ray binary. The QPO is detected at 0.08 Hz in the IR as well as two optical bands (U and V). Interestingly, these QPOs are at half the X-ray QPO frequency at 0.16 Hz, which is classified as the type-C QPO; a weak sub-harmonic close to the IR and optical QPO frequency is also detected in X-rays. The band-limited sub-second time-scale variability is strongly correlated in IR/X-ray bands, with X-rays leading the IR by over 120 ms. This short time delay, shape of the cross-correlation function and spectral energy distribution strongly indicate that this band-limited variable IR emission is the synchrotron emission from the jet. A jet origin for the IR QPO is strongly favoured, but cannot be definitively established with the current data. The spectral energy distribution indicates a thermal disc origin for the bulk of the optical emission, but the origin of the optical QPO is unclear. We discuss our findings in the context of the existing models proposed to explain the origin of variability.
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|Publisher Web site:||https://doi.org/10.1093/mnras/stw1211|
|Publisher statement:||This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.|
|Date accepted:||17 May 2016|
|Date deposited:||18 April 2018|
|Date of first online publication:||23 May 2016|
|Date first made open access:||18 April 2018|
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