Multitemperature Blackbody Spectrum of a Thin Accretion Disk around a Kerr Black Hole: Model Computations and Comparison with Observations

Li, Lixin; Zimmerman, Erik R.; Narayan, Ramesh; McClintock, Jeffrey E.

doi:10.1086/428089

Cited by 429 publications

(476 citation statements)

References 58 publications

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“…1, the adopted accretion disk model assumes a non-rotating BH, although the chosen value of the radiation efficiency, η = 0.1, is above the maximum efficiency for a Schwarzschild BH. However, using the Li et al (2005) software package, Calderone et al (2013) found that the Shakura & Sunyaev (1973) model with R = 3R S , as used here, mimics the SED for an optically thick, geometrically thin accretion disk around a Kerr BH quite well with a spin parameter a 0.7, corresponding to a maximum radiative efficiency η = 0.1. For this choice of η our BH mass estimates are therefore affected little by having neglected the general relativistic effects associated with a Kerr BH.…”

Section: Sed Modelingmentioning

confidence: 85%

Black-hole mass estimates for a homogeneous sample of bright flat-spectrum radio quasars

Castignani

Haardt

Lapi

et al. 2013

A&A

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We have selected a complete sample of flat-spectrum radio quasars (FSRQs) from the WMAP 7 yr catalog within the SDSS area, all with measured redshift, and compared the black-hole mass estimates based on fitting a standard accretion disk model to the "blue bump" with those obtained from the commonly used single-epoch virial method. The sample comprises 79 objects with a flux density limit of 1 Jy at 23 GHz, 54 of which (68%) have a clearly detected "blue bump". Thirty-four of those 54 have, in the literature, black-hole mass estimates obtained with the virial method. The mass estimates obtained from the two methods are well correlated. If the calibration factor of the virial relation is set to f = 4.5, well within the range of recent estimates, the mean logarithmic ratio of the two mass estimates is equal to zero with a dispersion close to the estimated uncertainty of the virial method. That the two independent methods agree so closely in spite of the potentially large uncertainties associated with each lends strong support to both of them. The distribution of black-hole masses for the 54 FSRQs in our sample with a well-detected blue bump has a median value of 7.4 × 10 8 M . It declines at the low-mass end, consistent with other indications that radio-loud AGNs are generally associated with the most massive black holes, although the decline may be, at least partly, due to the source selection. The distribution drops above log(M • /M ) = 9.4, implying that ultra-massive black holes associated with FSRQs must be rare.

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Section: Sed Modelingmentioning

confidence: 85%

Black-hole mass estimates for a homogeneous sample of bright flat-spectrum radio quasars

Castignani

Haardt

Lapi

et al. 2013

A&A

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“…The calculation of the thermal spectrum of a thin accretion disk has been extensively discussed in the literature; see e.g. Li et al (2005) and references therein for the Kerr case, and Bambi & Barausse (2011a), Chen & Jing (2012a) and Bambi (2012f) for a background with generic deviations from the Kerr solution. The spectrum can be conveniently written in terms of the photon flux number density as measured by a distant observer, N E obs .…”

Section: Continuum-fitting Methodsmentioning

confidence: 99%

Testing the space-time geometry around black hole candidates with the available radio and X-ray data

Bambi

2013

Astronomical Review

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Astrophysical black hole candidates are thought to be the Kerr black holes predicted by General Relativity, but the actual nature of these objects has still to be proven. The Kerr black hole hypothesis can be tested by observing strong gravity features and check if they are in agreement with the predictions of General Relativity. In particular, the study of the properties of the electromagnetic radiation emitted by the gas of the accretion disk can provide information on the geometry of the space-time around these objects and constrain possible deviations from the Kerr background.

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“…Scaling this value up to a rotation of 581 Hz gives a * ≃ 0.27. To test whether the direct disc emission in the spectrum of 4U 1636-53 is significantly affected by relativistic effects we tried, instead of the diskbb, a multi-temperature blackbody model for a thin, general relativistic accretion disc in a Kerr metric, which also includes self-irradiation (kerrbb; Li et al 2005). However, using the kerrbb, assuming a distance of 6.5 kpc, a NS mass of 1.4 M⊙, and a * = 0.27, did not significantly improve the fit.…”

Section: Direct Emissionmentioning

confidence: 99%

Broad iron line in the fast spinning neutron-star system 4U 1636−53

Sanna

Hiemstra

Méndez

et al. 2013

Monthly Notices of the Royal Astronomical Society

111

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We analysed the X-ray spectra of six observations, simultaneously taken with XMMNewton and Rossi X-ray Timing Explorer (RXTE), of the neutron star low-mass X-ray binary 4U 1636-53. The observations cover several states of the source, and therefore a large range of inferred mass accretion rate. These six observations show a broad emission line in the spectrum at around 6.5 keV, likely due to iron. We fitted this line with a set of phenomenological models of a relativistically broadened line, plus a model that accounts for relativistically smeared and ionised reflection from the accretion disc. The latter model includes the incident emission from both the neutronstar surface or boundary layer and the corona that is responsible for the high-energy emission in these systems. From the fits with the reflection model we found that in four out of the six observations the main contribution to the reflected spectrum comes from the neutron-star surface or boundary layer, whereas in the other two observations the main contribution to the reflected spectrum comes from the corona. We found that the relative contribution of these two components is not correlated to the state of the source. From the phenomenological models we found that the iron line profile is better described by a symmetric, albeit broad, profile. The width of the line cannot be explained only by Compton broadening, and we therefore explored the case of relativistic broadening. We further found that the direct emission from the disc, boundary layer, and corona generally evolved in a manner consistent with the standard accretion disc model, with the disc and boundary layer becoming hotter and the disc moving inwards as the source changed from the hard in to the soft state. The iron line, however, did not appear to follow the same trend.

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Multitemperature Blackbody Spectrum of a Thin Accretion Disk around a Kerr Black Hole: Model Computations and Comparison with Observations

Cited by 429 publications

References 58 publications

Black-hole mass estimates for a homogeneous sample of bright flat-spectrum radio quasars

Black-hole mass estimates for a homogeneous sample of bright flat-spectrum radio quasars

Testing the space-time geometry around black hole candidates with the available radio and X-ray data

Broad iron line in the fast spinning neutron-star system 4U 1636−53

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