Correlation between the photon index and X-ray luminosity of black hole X-ray binaries and active galactic nuclei: observations and interpretation

Yang, Qi Xiang; Xie, Fu-Guo; Yuan, Feng; Zdziarski, A. A.; Gierliński, Marek; Ho, Luis C.; Zhang, Yu

doi:10.1093/mnras/stu2571

Cited by 123 publications

(115 citation statements)

References 147 publications

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“…It is somewhat surprising to find such a hard spectrum at the very low Eddington luminosity observed. Typically the photon index decreases with decreasing flux only down to a transitional luminosity of ∼1% L Edd , after which the photon index begins to increase again with lower luminosities (see, e.g., Tomsick et al 2001;Wu & Gu 2008;Yang et al 2015). During quiescence the photon index has been seen to increase to Γ ≥ 2 (Corbel et al 2006;Plotkin et al 2013).…”

Section: Discussionmentioning

confidence: 99%

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GRS 1739-278 OBSERVED AT VERY LOW LUMINOSITY WITH XMM-NEWTON AND NuSTAR

Tomsick

Yamaoka

Dauser³

et al. 2016

ApJ

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We present a detailed spectral analysis of XMM-Newton and NuSTAR observations of the accreting transient black hole GRS 1739−278 during a very faint low hard state at ∼0.02% of the Eddington luminosity (for a distance of 8.5 kpc and a mass of 10 M ). The broad-band X-ray spectrum between 0.5-60 keV can be welldescribed by a power law continuum with an exponential cutoff. The continuum is unusually hard for such a low luminosity, with a photon index of Γ = 1.39 ± 0.04. We find evidence for an additional reflection component from an optically thick accretion disk at the 98% likelihood level. The reflection fraction is low with R refl = 0.043 +0.033 −0.023 . In combination with measurements of the spin and inclination parameters made with NuSTAR during a brighter hard state by Miller and co-workers, we seek to constrain the accretion disk geometry. Depending on the assumed emissivity profile of the accretion disk, we find a truncation radius of 15-35 R g (5-12 R ISCO ) at the 90% confidence limit. These values depend strongly on the assumptions and we discuss possible systematic uncertainties.

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Section: Discussionmentioning

confidence: 99%

“…This may indicate that thermal Comptonization in an optically thin plasma is still the dominating effect in GRS 1739−278, even though a strong radio jet is present (e.g., Loh et al, in prep. ), as a jet-dominated synchrotron spectrum would result in a softer photon index (Esin et al 1997;Yang et al 2015).…”

Section: Discussionmentioning

confidence: 99%

GRS 1739-278 OBSERVED AT VERY LOW LUMINOSITY WITH XMM-NEWTON AND NuSTAR

Tomsick

Yamaoka

Dauser³

et al. 2016

ApJ

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“…As BHXBs fade from the low-hard state toward quiescence, their X-ray spectra become softer (e.g., Tomsick et al 2001Tomsick et al , 2004Kalemci et al 2005;Wu & Gu 2008;Sobolewska et al 2011;Armas Padilla et al 2013) until they display G » 2.1 (e.g., Kong et al 2002;Corbel et al 2006;Plotkin et al 2013;Armas Padilla et al 2014;Reynolds et al 2014;Yang et al 2015). From an ensemble of quiescent BHXBs, Plotkin et al (2013) argue that the X-ray spectral softening completes by -L 10 5…”

Section: Introductionmentioning

confidence: 99%

The 2015 Decay of the Black Hole X-Ray Binary V404 Cygni: Robust Disk-Jet Coupling and a Sharp Transition Into Quiescence

Plotkin

Miller-Jones

Gallo

et al. 2017

ApJ

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We present simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cygni at the end of its 2015 outburst. From 2015 July 11-August 5, we monitored V404 Cygni with Chandra, Swift, and NuSTAR in the X-ray, and with the Karl G. Jansky Very Large Array and the Very Long Baseline Array in the radio, spanning a range of luminosities that were poorly covered during its previous outburst in 1989 (our 2015 campaign covers10 erg s 33 X 34 1 ). During our 2015 campaign, the X-ray spectrum evolved rapidly from a hard photon index of). We argue that V404 Cygni reaching G » 2 marks the beginning of the quiescent spectral state, which occurs at a factor of ≈3-4 higher X-ray luminosity than the average pre-outburst luminosity of »´-8 10 erg s 32 1. V404 Cygni falls along the same radio/X-ray luminosity correlation that it followed during its previous outburst in 1989, implying a robust disk-jet coupling. We exclude the possibility that a synchrotron-cooled jet dominates the X-ray emission in quiescence, leaving synchrotron self-Compton from either a hot accretion flow or from a radiatively cooled jet as the most likely sources of X-ray radiation, and/or particle acceleration along the jet becoming less efficient in quiescence. Finally, we present the first indications of correlated radio and X-ray variability on minute timescales in quiescence, tentatively measuring the radio emission to lag the X-ray by  15 4 minute, suggestive of X-ray variations propagating down a jet with alength of<3.0 au.

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“…In modeling the SED of quiescent BHs with ADAF-jet model, Xie et al (2014) suggested that the X-ray emission of V404 Cyg in quiescent state should be dominated by jet based on its X-ray shape (see also Yuan et al 2009, for a couple of quiescent supermassive BHs), where jet produce power-law X-ray spectrum while the inverse-Compton spectrum from ADAF is normally curved. The soften of X-ray spectrum in quiescent BHs can be explained by both ADAF and jet models separately, where the bremsstrahlung radiation will contribute to X-ray emission (Esin et al 1997) while the synchrotron emission normally produce a power-law X-ray with Γ ∼ 2 (e.g., Yuan et al 2009;Xie et al 2014;Yang et al 2015). Broadband X-ray observation in quiescent BHs and better dealing with Comptonization in ADAF are expected to further test this issue.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Based on these similarities, Dong et al (2014) Merloni et al (2003) and Dong et al (2014) with much different slopes of ξX are most possibly regulated by radiatively inefficient and radiatively efficient BH sources respectively. Yang et al (2015) proposed that the X-ray emission in quiescent state may be dominated by the jet and the value of Γ should keep as a constant while the X-ray emission dominantly come from ADAF in LH state. The spectral energy distribution (SED) modeling also preferred the pure jet model for these quiescent BHs (e.g., Xie et al 2014;Plotkin et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Revisit the Fundamental Plane of black hole activity from sub-Eddington to quiescent state

Dong¹,

Wu²

2015

Mon. Not. R. Astron. Soc.

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It is very controversial whether radio-X-ray correlation as defined in low-hard state of X-ray binaries (XRBs) can extend to quiescent state (e.g., X-ray luminosity less than a critical value of L X,c ∼ 10 −5.5 L Edd ) or not. In this work, we collect a sample of XRBs and low luminosity active galactic nuclei (LLAGNs) with wide distribution of Eddington ratios (L X /L Edd ∼ 10 −9 − 10 −3 ) to reexplore the fundamental plane between 5 GHz radio luminosity, L R , 2-10 keV X-ray luminosity, L X , and black hole (For the whole sample, we confirm the former fundamental plane of Merloni et al. and Falcke et al. that ξ X ∼ 0.6 and ξ M ∼ 0.8 even after including more quiescent BHs. The quiescent BHs follow the fundamental plane very well, and, however, FR I radio galaxies follow a steeper track comparing other BH sources. After excluding FR Is, we investigate the fundamental plane for BHs in quiescent state with L X < L X,c and sub-Eddington BHs with L X > L X,c respectively, and both subsamples have a similar slope, ξ X ∼ 0.6, which support that quiescent BHs may behave similar to those in low-hard state. We further select two subsamples of AGNs with BH mass in a narrow range (FR Is with M BH = 10 8.8±0.4 and other LLAGNs with M BH = 10 8.0±0.4 ) to simulate the behavior of a single supermassive BH evolving from sub-Eddington to quiescent state. We find that the highly sub-Eddington sources with L X /L Edd ∼ 10 −6 − 10 −9 still roughly stay on the extension of radio-X-ray correlation as defined by other sub-Eddington BHs. Our results are consistent with several recent observations in XRBs that the radio-X-ray correlation as defined in lowhard state can extend to highly sub-Eddington quiescent state.

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Correlation between the photon index and X-ray luminosity of black hole X-ray binaries and active galactic nuclei: observations and interpretation

Cited by 123 publications

References 147 publications

GRS 1739-278 OBSERVED AT VERY LOW LUMINOSITY WITH XMM-NEWTON AND NuSTAR

GRS 1739-278 OBSERVED AT VERY LOW LUMINOSITY WITH XMM-NEWTON AND NuSTAR

The 2015 Decay of the Black Hole X-Ray Binary V404 Cygni: Robust Disk-Jet Coupling and a Sharp Transition Into Quiescence

Revisit the Fundamental Plane of black hole activity from sub-Eddington to quiescent state

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