Relativistic Accretion Disk Models of High‐State Black Hole X‐Ray Binary Spectra

Davis, Shane W.; Blaes, Omer; Hubený, I.; Turner, Neal J.

doi:10.1086/427278

Cited by 270 publications

(352 citation statements)

References 41 publications

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“…The colour correction factor was found by Shimura & Takahara (1995) to be in the range of κ ≃1.7-2, with somewhat lower values found by Davis et al (2005), see their table 1. We note that the inner disc temperature of diskbb, T in , has now the interpretation of the colour temperature, while the effective temperature equals T in /κ.…”

Section: Modification Of the Disc Blackbody Modelmentioning

confidence: 84%

Spectral analysis of theXMM–Newtondata of GX 339–4 in the low/hard state: disc truncation and reflection

Basak¹,

Zdziarski²

2016

Mon. Not. R. Astron. Soc.

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We analyse all available observations of GX 339-4 by XMM-Newton in the hard spectral state. We jointly fit the spectral data by Comptonization and the currently best reflection code, relxill. We consider in detail a contribution from a standard blackbody accretion disc, testing whether its inner radius can be set equal to that of the reflector. However, this leads to an unphysical behaviour of the disc truncation radius, implying the soft X-ray component is not a standard blackbody disc. This appears to be due to irradiation by the hard X-rays, which strongly dominate the total emission. We consider a large array of models, testing, e.g., the effects of the chosen energy range, of adding unblurred reflection, and assuming a lamppost geometry. We find the effects of relativistic broadening to be relatively weak in all cases. In the coronal models, we find the inner radius to be large. In the lamppost model, the inner radius is unconstrained, but when fixed to the innermost stable orbit, the height of the source is large, which also implies a weak relativistic broadening. In the former models, the inner radius correlates with the X-ray hardness ratio, which is consistent with the presence of a truncated disc turning into a complete disc in the soft state. We also find the degree of the disc ionization to anti-correlate with the hardness, leading to strong spectral broadening due to scattering of reflected photons in the reflector in the softest studied states.

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Section: Modification Of the Disc Blackbody Modelmentioning

confidence: 84%

Spectral analysis of theXMM–Newtondata of GX 339–4 in the low/hard state: disc truncation and reflection

Basak¹,

Zdziarski²

2016

Mon. Not. R. Astron. Soc.

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“…In black hole accretion disks, for example, the most detailed of such models so far are those of Hubeny et al (2001) for supermassive black holes, Davis et al (2005) for stellar mass black holes, and Hui et al (2005) for intermediate mass black holes. The models fully account for relativistic effects, and include a detailed non-LTE treatment of level populations of hydrogen, helium, and abundant metals.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, in radiation-pressure-dominated simulations of MRI turbulence, dissipation of compressive motions by photon diffusion is fully resolved (Turner et al 2003). Davis et al (2005) used the time-and horizontally averaged vertical dissipation profile from the simulation of Turner (2004) to compute the vertical structure and spectrum of an annulus, and compared it to a model based on the usual ad hoc assumption of constant dissipation per unit mass. While the resulting profiles of density and temperature were very different, the emergent spectrum was very similar.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Pressure Support and Accretion Disk Spectra

Blaes

Davis

Hirose

et al. 2006

ApJ

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Stellar atmosphere models of ionized accretion disks have generally neglected the contribution of magnetic fields to the vertical hydrostatic support, although magnetic fields are widely believed to play a critical role in the transport of angular momentum. Simulations of magnetorotational turbulence in a vertically stratified shearing box geometry show that magnetic pressure support can be dominant in the upper layers of the disk. We present calculations of accretion disk spectra that incorporate vertical magnetic pressure and dissipation profiles derived from the radiation magnetohydrodynamical simulation of Hirose, Krolik, & Stone. Magnetic pressure support generically produces a more vertically extended disk atmosphere with a larger density scale height. This acts to harden the spectrum compared to models that neglect magnetic pressure support. We estimate the significance of this effect on disk-integrated spectra by calculating an illustrative disk model for a stellar mass black hole, assuming that similar magnetic pressure support exists at all radii.

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“…In the last decade, several authors (e.g. Sincell & Krolik 1998;Hubeny et al 2001;Davis et al 2005;Hui et al 2005) have applied a constant dissipation rate per unit mass. We follow this investigating a class of models using the following formula for the flux generation rate:…”

Section: Dissipation Profilesmentioning

confidence: 99%

“…They also assume an ad hoc energy dissipation law (e.g. Davis et al 2005;Różańska & Madej 2008;Idan et al 2008). In most cases, radiative transfer with all the important absorption and scattering processes included is implemented on the disk surface, while the deepest parts of the disk are treated in the diffusion approximation.…”

Section: Introductionmentioning

confidence: 99%

Vertical dissipation profiles and the photosphere location in thin and slim accretion disks

Sądowski

Abramowicz

Bursa

et al. 2009

A&A

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As several authors in the past, we calculate optically thick but geometrically thin (and slim) accretion disk models and perform a ray-tracing of photons in the Kerr geometry to calculate the observed disk continuum spectra. Previously, it was common practice to ray-trace photons assuming that they are emitted from the Kerr geometry equatorial plane, z = 0. We show that the continuum spectra calculated with this assumption differ from these calculated under the assumption that photons are emitted from the actual surface of the disc, z = H(r). This implies that a knowledge of the location of the thin disk effective photosphere is relevant for calculating the continuum emission. In this paper we investigate, in terms of a simple model, a possible influence of the (unknown, and therefore assumed ad hoc) vertical dissipation profiles on the vertical structure of the disk and thus on the location of the effective photosphere, and on the observed continuum spectra. For disks with moderate and high mass accretion rates (ṁ > 0.01ṁ C ), we find that the photosphere location in the inner, radiation pressure dominated, disk region (where most of the radiation comes from) does not depend on the dissipation profile and therefore emerging disk spectra are insensitive to the choice of the dissipation function. For lower accretion rates, the photosphere location depends on the assumed vertical dissipation profile down to the disk inner edge, but the dependence is very weak and thus of minor importance. We conclude that the continuum spectra of optically thick accretion disks around black holes should be calculated with ray-tracing from the effective photosphere and that, fortunately, the choice of a particular vertical dissipation profile does not substantially influence the calculated emission.

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Relativistic Accretion Disk Models of High‐State Black Hole X‐Ray Binary Spectra

Cited by 270 publications

References 41 publications

Spectral analysis of theXMM–Newtondata of GX 339–4 in the low/hard state: disc truncation and reflection

Spectral analysis of theXMM–Newtondata of GX 339–4 in the low/hard state: disc truncation and reflection

Magnetic Pressure Support and Accretion Disk Spectra

Vertical dissipation profiles and the photosphere location in thin and slim accretion disks

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