Discovery of a broad iron line in the black hole candidate Swift J1753.5−0127, and the disc emission in the low/hard state revisited

Hiemstra, Beike; Soleri, P.; Méndez, Mariano; Belloni, T.; Mostafa, Reham; Wijnands, Rudy

doi:10.1111/j.1365-2966.2009.14461.x

Cited by 36 publications

(54 citation statements)

References 49 publications

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“…11; there are no solutions in this range for a disc with ξ∼ 5000 erg cm s −1 . We conclude that the high‐ionization solution found by Hiemstra et al (2009) is physically inconsistent; the disc must extend in to small radii.…”

Section: Acknowledgmentsmentioning

confidence: 70%

“…With an estimated mass of approximately 10 M ⊙ (Cadolle Bel et al 2007), a radius of 255 r g is the equivalent of a disc truncated at ≈3.8 × 10 8 cm from the central black hole. Using the ionization parameter and unabsorbed flux presented in Hiemstra et al (2009), we can estimate the hydrogen number density to be approximately 2.3 × 10 15 cm −3 . A modest surface layer of Thomson depth will thus result in a disc with a half thickness, t > 2 × 10 9 cm; at least five times larger than the truncation radius.…”

Section: Acknowledgmentsmentioning

confidence: 98%

“…Note added after submission: Hiemstra et al (2009) have analysed the same XMM–Newton and RXTE data for J1753.5−0127 used here. They independently confirm the existence of a broad Fe‐Kα line and show that various continuum models with the addition of a laor line can successfully fit the data.…”

Section: Acknowledgmentsmentioning

confidence: 99%

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Determining the spin of two stellar-mass black holes from disc reflection signatures

Reis¹,

Fabian²,

Ross³

et al. 2009

Monthly Notices of the Royal Astronomical Society

118

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We present measurements of the dimensionless spin parameters and inner‐disc inclination of two stellar‐mass black holes. The spin parameter of SWIFT J1753.5−0127 and GRO J1655−40 is estimated by modelling the strong reflection signatures present in their XMM–Newton observations. Using a newly developed, self‐consistent reflection model which includes the blackbody radiation of the disc as well as the effect of Comptonization, blurred with a relativistic line function, we infer the spin parameter of SWIFT J1753.5−0127 to be 0.76+0.11−0.15. The inclination of this system is estimated at 55°+2−7. For GRO J1655−40, we find that the disc is significantly misaligned to the orbital plane, with an innermost inclination of 30°+5−10. Allowing the inclination to be a free parameter, we find a lower limit for the spin of 0.90, this value increases to that of a maximal rotating black hole when the inclination is set to that of the orbital plane of J1655−40. Our technique is independent of the black hole mass and distance, uncertainties in which are among the main contributors to the spin uncertainty in previous works.

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Section: Acknowledgmentsmentioning

confidence: 70%

Section: Acknowledgmentsmentioning

confidence: 98%

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Determining the spin of two stellar-mass black holes from disc reflection signatures

Reis¹,

Fabian²,

Ross³

et al. 2009

Monthly Notices of the Royal Astronomical Society

118

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“…A similar spectral decomposition is also possible for black hole sources in their low/hard states, where a very soft component, together with a reflection component arising in an untruncated accretion disk, is claimed to be present by some authors (Miller et al 2006b,a;Rykoff et al 2007), but it is rejected by others (Done & Gierliński 2006;D'Angelo et al 2008;Gierliński et al 2008;Hiemstra et al 2009;Cabanac et al 2009). However, in black holes, there is no balance required in the energetics of the components that make up the overall X-ray emission, as the quantity of energy advected beyond the event horizon is an unknown variable.…”

Section: Modelmentioning

confidence: 72%

A self-consistent approach to the hard and soft states of 4U 1705-44

D’Aí¹,

Salvo²,

Ballantyne

et al. 2010

A&A

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Context. High-resolution spectroscopy has recently revealed in many low-mass X-ray binaries hosting a neutron star that the shape of the broad iron line observed in the 6.4-6.97 keV range is consistently well-fitted by a relativistically smeared line profile. Aims. The presence of other broad features, besides the iron line, together with a high S/N of the spectra offer the possibility of testing a self-consistent approach to the overall broadband reflection spectrum and evaluating the impact of the reflection component in the formation of the broadband X-ray spectra. Methods. We analyzed two XMM-Newton observations of the bright atoll source 4U 1705-44, which can be considered a prototype of the class of the persistent NS LMXBs showing both hard and soft states. The first observation was performed when the source was in a hard low flux state, the second during a soft, high-flux state. Both the spectra show broad iron emission lines. We fit the spectra using a two-component model, together with a reflection model specifically suited to the case of a neutron star, where the incident spectrum has a blackbody shape. Results. In the soft state, the reflection model, convolved with a relativistic smearing component, consistently describes the broad features present in the spectrum, and we find a clear relation between the temperature of the incident flux and the temperature of the harder X-ray component that we interpret as the boundary layer emission. In this state we find converging evidence that the boundary layer outer radius is ∼2 times the neutron star radius. In the low flux state, we observe a change in the continuum shape of the spectrum with respect to the soft state. Still, the broad local emission features can be associated with a disk reflecting matter, but in a lower ionization state, and possibly produced in an accretion disk truncated at greater distance. Conclusions. Our analysis provides strong evidence that the reflection component in soft states of LMXBs comes from to hard X-ray thermal irradiation, which we identify with the boundary layer emission, also present in the continuum model. In the hard state, the broad iron line if also produced by reflection, and the continuum disk emission can be self-consistently accounted if the disk is truncated at a greater distance than the soft state.

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“…Hiemstra et al (2009) re-analyzed the data from Miller et al (2006a) and find that while it is consistent with containing a soft disk component, a number of alternative continuum prescriptions that allow the disk to be truncated are also valid; however, see Reis et al (2009) and Wilkinson & Uttley (2009) who outline a number of issues with this result. Gierlinski et al (2008) propose a scenario in which the disk is truncated at larger radii; however, the inner edge of the disk is irradiated by the high-energy Comptonized photons in the corona.…”

Section: Alternatives To a Thin Disk At The Iscomentioning

confidence: 99%

SUZAKUBROADBAND SPECTROSCOPY OFSWIFTJ1753.5–0127 IN THE LOW-HARD STATE

Reynolds

Miller

Homan

et al. 2009

ApJ

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We present Suzaku observations of the Galactic black hole candidate Swift J1753.5−0127 in the low-hard state (LHS). The broadband coverage of Suzaku enables us to detect the source over the energy range 0.6-250 keV. The broadband spectrum (2-250 keV) is found to be consistent with a simple power-law (Γ ∼ 1.63). In agreement with previous observations of this system, a significant excess of soft X-ray flux is detected consistent with the presence of a cool accretion disk. Estimates of the disk inner radius infer a value consistent with the innermost stable circular orbit (ISCO; R in 6R g , for certain values of, e.g., N H , i), although we cannot conclusively rule out the presence of an accretion disk truncated at larger radii (R in ∼ 10-50R g ). A weak, relativistically broadened iron line is also detected, in addition to disk reflection at higher energy. However, the iron-K line profile favors an inner radius larger than the ISCO (R in ∼ 10-20R g ). The implications of these observations for models of the accretion flow in the LHS are discussed.

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Discovery of a broad iron line in the black hole candidate Swift J1753.5−0127, and the disc emission in the low/hard state revisited

Cited by 36 publications

References 49 publications

Determining the spin of two stellar-mass black holes from disc reflection signatures

Determining the spin of two stellar-mass black holes from disc reflection signatures

A self-consistent approach to the hard and soft states of 4U 1705-44

SUZAKUBROADBAND SPECTROSCOPY OFSWIFTJ1753.5–0127 IN THE LOW-HARD STATE

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