Non-lte spectra of accretion disks around intermediate-mass black holes

Yawei Hui, Julian H. Krolik, Ivan - Hubeny

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

We have calculated the structures and the emergent spectra of stationary, geometrically thin accretion disks around 100 and 1000 M black holes in both the Schwarzschild and extreme Kerr metrics. Equations of radiative transfer, hydrostatic equilibrium, energy balance, ionization equilibrium, and statistical equilibrium are solved simultaneously and consistently. The six most astrophysically abundant elements (H, He, C, N, O, and Fe) are included, as well as energy transfer by Comptonization. The observed spectrum as a function of viewing angle is computed, incorporating all general relativistic effects. We find that, in contrast with the predictions of the commonly used multicolor disk (MCD) model, opacity associated with photoionization of heavy elements can significantly alter the spectrum near its peak. These ionization edges can create spectral breaks visible in the spectra of slowly spinning black holes viewed from almost all angles and in the spectra of rapidly spinning black holes seen approximately pole-on. For fixed mass and accretion rate relative to Eddington, both the black hole spin and the viewing angle can significantly shift the observed peak energy of the spectrum, particularly for rapid spin viewed obliquely or edge-on. We present a detailed test of the approximations made in various forms of the MCD model. Linear limb-darkening is confirmed to be a reasonable approximation for the integrated flux but not for many specific frequencies of interest.

Original languageEnglish (US)
Pages (from-to)913-922
Number of pages10
JournalAstrophysical Journal
Volume625
Issue number2 I
DOIs
StatePublished - Jun 1 2005

Fingerprint

accretion disks
accretion
metal spinning
ionization
limb darkening
heavy elements
relativistic effects
hydrostatics
opacity
approximation
radiative transfer
energy balance
energy
limb
photoionization
poles
energy transfer
shift
prediction
predictions

Keywords

  • Accretion, accretion disks
  • Black hole physics
  • Radiative transfer
  • X-rays: general

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Non-lte spectra of accretion disks around intermediate-mass black holes. / Hui, Yawei; Krolik, Julian H.; Hubeny, Ivan -.

In: Astrophysical Journal, Vol. 625, No. 2 I, 01.06.2005, p. 913-922.

Research output: Contribution to journalArticle

Hui, Yawei ; Krolik, Julian H. ; Hubeny, Ivan -. / Non-lte spectra of accretion disks around intermediate-mass black holes. In: Astrophysical Journal. 2005 ; Vol. 625, No. 2 I. pp. 913-922.
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