Emergent Spectra From Disks Surrounding Kerr Black Holes: Effect of Photon Trapping and Disk Self-Shadowing

Abstract

Based on a new estimation of their thickness, the global properties of relativistic slim accretion disks are investigated in this work. The resulting emergent spectra are calculated using the relativistic ray-tracing method, in which we neglect the self-irradiation of the accretion disk. The angular dependence of the disk luminosity, the effects of the heat advection and the disk thickness on the estimation of the black hole spin are discussed. Compare to the previous works, our improvements are that we use the self-consistent disk equations and we consider the disk self-shadowing effect. We find that at the moderate accretion rate, the radiation trapped in the outer region of the accretion disks will escape in the inner region of the accretion disk and contribute to the emergent spectra. At the high accretion rate, for the large inclination and large black hole spin, both the disk thickness and the heat advection have significant influence on the emergent spectra. Consequently, these effects will influence the measurement of the black hole spin based on the spectra fitting and influence the angular dependence of the luminosity. For the disks around Kerr black holes with $a=0.98$, if the disk inclination is greater than $60^{\circ }$, and their luminosity is beyond 0.2 Eddington luminosity, the spectral model which is based on the relativistic standard accretion disk is no longer applicable for the spectra fitting. We also confirm that the effect of the self-shadowing is significantly enhanced by the light-bending, which implies that the non-relativistic treatment of the self-shadowing is inaccurate. According to our results, the observed luminosity dependence of the measured spin suggests that the disk self-shadowing significantly shapes the spectra of GRS 1915+105, which might lead to the underestimation of the black hole spin for the high luminosity states.

13 pages, 11 figures. Apj Accepted

References in corpus (8)

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• Testing Accretion Disk Theory in Black Hole X-ray Binaries
• Dependence of inner accretion disk stress on parameters: the Schwarzschild case
• Slim disks around Kerr black holes revisited
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• Spectral energy distribution of super-Eddington flows

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• Measuring Black Hole Spin by the Continuum-Fitting Method: Effect of Deviations from the Novikov-Thorne Disc Model
• Confronting the models of 3:2 quasiperiodic oscillations with the rapid spin of the microquasar GRS 1915+105
• Self-shadowing Effects of Slim Accretion Disks in Active Galactic Nuclei: Diverse Appearance of the Broad-line Region
• The Eye of the Storm: Light from the Inner Plunging Region of Black Hole Accretion Discs
• Constraining spins of supermassive black holes from TeV variability. II. fully general relativistic calculations
• X-ray observational signature of a black hole accretion disc in an active galactic nucleus RXJ1633+4718
• An accretion disk-outflow model for hysteretic state transition in X-ray binaries
• Limits on luminosity and mass accretion rate of a radiation pressure dominated accretion disc
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