A Unified Description of the Timing Features of Accreting X-Ray Binaries

By T. Belloni, Dimitrios Psaltis, M. van der Klis. 2002

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We study an empirical model for a unified description of the power spectra of accreting neutron stars and black holes. This description is based on a superposition of multiple Lorentzians and offers the advantage that all quasi-periodic oscillation and noise components are dealt with in the same way, without the need of deciding in advance the nature of each component. This approach also allows us to compare frequencies of features with high and low coherences in a consistent manner and greatly facilitates comparison of power spectra across a wide range of source types and states. We apply the model to six sources: the low-luminosity X-ray bursters 1E 1724-3045, SLX 1735-269, and GS 1826-24; the high-latitude transient XTE J1118+480; the bright system Cir X-1; and the Z source GX 17+2. We find that it provides a good description of the observed spectra without the need for a scale-free (1/f) component. We update previously reported correlations between characteristic frequencies of timing features in the light of this new approach and discuss similarities between different types of systems that may point toward similar underlying physics.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/b7b4b28b2cfcdff59d6af79249c6a275ab2f520b

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Citations in the corpus

Modelling the behaviour of accretion flows in X-ray binaries (2007, background): “27), which show the same correlations between frequencies as for the black holes (Psaltis et al. 1999; Wijnands & van der Klis 1999; Belloni et al. 2002; van der Klis 2004).”
The evolution of the timing properties of the black-hole transient GX 339-4 during its 2002/2003 outburst (2005, neutral): “The power spectra can be decomposed in a small number of flat-top (or broad) components, approximated with Lorentzian functions, plus at times a low-frequency quasi-periodic oscillation (QPO; see Nowak 2000; Psaltis et al. 1999; Belloni et al. 2002; Pottschmidt et al. 2004).”
A study of the low-frequency quasi-periodic oscillations in the X-ray light curves of the black hole candidate XTE J1859+226 (2004, methodology): “Following Belloni et al. 2002, we fitted the noise components with two Lorentzian shapes, one zerocentered and a second one centered at a few Hz.”
High-frequency quasi-periodic oscillations in black hole binaries (2012, background): “The similarities between the timing features of these two classes of sources are strong (see Wijnands et al. 1999; Psaltis et al. 1999; Belloni et al. 2002; van der Klis 2006), but it is not clear how HFQPOs fit in this comparison.”
Precise mass and spin measurements for a stellar-mass black hole through X-ray timing: the case of GRO J1655-40 (2013, methodology): “(i) A zero-centred low-frequency Lorentzian (defined Lb, see Belloni et al. 2002 and Fig.”
Rapid optical and X-ray timing observations of GX 339-4: multi-component optical variability in the low/hard state (2010, background): “The X-ray rms variability amplitude (Table 3) is high, but not unprecedented (e.g. Belloni et al. 2002).”
Low-frequency oscillations in black holes: a spectral-timing approach to the case of GX 339-4 (2011, methodology): “Following Belloni et al. (2002), we fitted the noise components withthree broad Lorentzian shapes, one zero-centered and other two centered at a few Hz.”
Long term variability of Cygnus X-1. I. X-ray spectral-temporal correlations in the hard state (2002, methodology): “…the lowest frequency Lorentzian, such as using a zero centered Lorentzian, i.e., a shot noise component featuring a single relaxation time scale (Belloni et al. 2002), may in principle provide fits of comparable quality (note that in the case of the observation analyzed by Nowak 2000, a zero…”
A review of quasi-periodic oscillations from black hole X-ray binaries: Observation and theory (2019, background): “[183] and [24] noted that broader power spectral components are observed in the hard state, whose characteristic frequencies smoothly evolve into the HF QPO frequencies as the source spectrum softens.”