The rms–flux relations in different branches in Cyg X-2

Li, Z. B.; Song, Liming; Qu, J. L.; Lei, Y. J.; Nie, Jundan; Zhang, C. M.

doi:10.1007/s10509-012-1086-6

Cited by 2 publications

(2 citation statements)

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“…For other broadband continuum components, which represent fast aperiodic variability, several models have been presented to explain this noise component, including the shot noise model, coronal flare model, and fluctuation propagation model (Terrell & James 1972;Nolan et al 1981;Belloni & Hasinger 1990;Mineshige et al 1994;Stern & Svensson 1996). Considering that the shot noise model predicts a stationary power spectrum and cannot produce a linear rms-flux relation for different timescales, it is not accepted to explain the broadband noise (Li et al 2012). Furthermore, Uttley (2004) showed that the rms-flux relation in the accreting millisecond pulsar SAX J1808.4-3658 is coupled with the 401 Hz pulsation.…”

Section: Introductionmentioning

confidence: 99%

“…This relation put a strict constrain on the origin of the rms-flux relation from magnetic caps of the neutron star, which means that the linear relation does not favor the coronal flare model for the X-ray variability. Up to now, the fluctuation propagation model is widely accepted because it naturally explains the rms-flux relation for different timescales, which is common in X-ray binaries (Uttley & McHardy 2001;Negoro & Mineshige 2002;Gleissner et al 2004;Uttley 2004;Uttley et al 2005;Li et al 2010Li et al , 2012. In the fluctuation propagation model (Lyubarskii 1997;Ingram & Done 2012;Ingram 2016;Mushtukov et al 2019), the broadband noise components are believed to break down at the local viscous frequency f visc ∝ 1/R 2 in a power spectrum with a Lorentzian shape ( ( ( )) )…”

Section: Introductionmentioning

confidence: 99%

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The Accretion Flow Geometry of MAXI J1820+070 through Broadband Noise Research with Insight Hard X-ray Modulation Telescope

Yang

Zhang

Bu³

et al. 2022

ApJ

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Here we present a detailed study of the broadband noise in the power density spectra of the black hole X-ray binary MAXI J1820+070 during the hard state of its 2018 outburst, using Hard X-ray Modulation Telescope observations. The broadband noise shows two main humps, which might separately correspond to variability from a variable disk and two Comptonization regions. We fitted the two humps with multiple Lorentzian functions and studied the energy-dependent properties of each component up to 90–150 keV and their evolution with spectral changes. The lowest-frequency component is considered as the subharmonic of the quasiperiodic oscillation component and shows a different energy dependence compared with other broadband noise components. We found that although the fractional rms of all the broadband noise components mainly decreases with the energy, their rms spectra are different in shape. Above ∼20–30 keV, the characteristic frequencies of these components increase sharply with the energy, meaning that the high-energy component is more variable on short timescales. Our results suggest that the hot inner flow in MAXI J1820+070 is likely to be inhomogeneous. We propose a geometry with a truncated accretion disk and two Comptonization regions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Accretion Flow Geometry of MAXI J1820+070 through Broadband Noise Research with Insight Hard X-ray Modulation Telescope

Yang

Zhang

Bu³

et al. 2022

ApJ

Self Cite

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Black hole-like hysteresis and accretion states in neutron star low-mass X-ray binaries

Muñoz-Darias

Fender

Motta

et al. 2014

Monthly Notices of the Royal Astronomical Society

142

137

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We have systematically studied a large sample of the neutron star low mass X-ray binaries (LMXBs) monitored by the Rossi X-ray Timing Explorer (50 sources; 10000+ observations). We find that the hysteresis patterns between Compton dominated and thermal dominated states, typically observed in black hole LMXBs, are also common in neutron star systems. These patterns, which also sample intermediate states, are found when looking at the evolution of both X-ray colour and fast variability of ten systems accreting below ∼ 30% of the Eddington Luminosity (L Edd ). We show that hysteresis does not require large changes in luminosity and it is the natural form that state transitions take at these luminosities. At higher accretion rates neutron stars do not show hysteresis, and they remain in a thermal dominated, low variability state, characterized by flaring behaviour and fast colour changes. Only at luminosities close to L Edd , are high variability levels seen again, in correspondence to an increase in the fractional contribution of the Comptonization component. We compare this behaviour with that observed in LMXBs harbouring black holes, showing that the spectral, timing and multi-wavelength properties of a given source can be determined by its location in the fast variability-luminosity diagram, which, therefore, provides a common framework for neutron star and black hole accretion states.

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The rms–flux relations in different branches in Cyg X-2

Cited by 2 publications

References 34 publications

The Accretion Flow Geometry of MAXI J1820+070 through Broadband Noise Research with Insight Hard X-ray Modulation Telescope

The Accretion Flow Geometry of MAXI J1820+070 through Broadband Noise Research with Insight Hard X-ray Modulation Telescope

Black hole-like hysteresis and accretion states in neutron star low-mass X-ray binaries

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