Ctorus model
This is an X-ray spectral model for clumpy tori in active galactic
nuclei, which is the output spectrum of a clumpy torus illuminated by
the central active galactic nuclei. This model is comprehensively
explained
in Liu,
Y., & Li, X. 2014, ApJ, 787, 52. See more applications
in Liu,
Y., & Li, X. 2015, MNRAS, 448, L53 and
Liu, J.,
Liu, Y., Li, X., et al. 2016, MNRAS, 459, L100.
The incident X-ray spectrum from the central active galactic nuclei is
a power law. The half-opening angle of the torus (the envelope of
clouds) is fixed at 60 degrees. This model can be applied in 1.0 - 450
keV and includes three parts, i.e., transmitted component
(Ctorus_T.fits), reflection component (Ctorus_R.fits), and fluorescent
lines (Ctorus_L.fits).
The transmitted component is the power law absorbed by a given column
density NH, which is the only parameter of this component. Since the
scattering cross section is included, the absorption is more
significant compared with wabs or phabs with the same value of
nominal NH.
- NH: the column density along our line of sight, in the
units of 10^23 cm^-2, from 0.1 to 100
The reflection component is the collection of photons that have
experienced the Compton and/or Rayleigh scattering with the torus.
- N: the average number of clouds along the radial direction, from 2 to 10
- NH: the total column density if N clouds are exactly aligned along the radial direction, in the units of 10^23 cm^-2, from 1 to 100.
- Costheta: the cosine value of observing angle (the angle between our line of sight and the rotation axis of the torus), from 0.05 (edge-on) to 0.95 (face-on).
- Gamma: the photon index of the incident power law, from 1.5 to 2.5
The parameters in the fluorescent lines are the same as those in
the reflection component. The current model has included the
Kalpha lines of Mg, Al, Si, S, Ar, Ca, Fe, and Ni, and the Kbeta lines
of Ca, Fe, and Ni. The Compton shoulder is not included in the current
version.
The basic usage of the Ctorus model is mtable{Ctorus_T.fits}*powerlaw
+ atable{Ctorus_R.fits} + atable{Ctorus_L.fits}
- Due to the clumpy geometry, the value of NH in the Ctorus_T is not necessarily the same as that in other components. Please see the subtle difference of several column densities in section 3 of Liu & Li (2014).
- The gamma and norm in Ctorus_T should be linked to the PhoIndex and norm in powerlaw, unless e.g. you think the incident spectrum from the active galactic nuclei is anisotropic (amplitude or shape).
- The parameters in Ctorus_L.fits should also be linked to those
in Ctorus_T in most cases.
An example is shown in Ctorus_test.xcm.
Keith Arnaud,
Lab. for High Energy Astrophysics, NASA/Goddard Space Flight Center
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Last modified: Friday, 27-May-2016 12:41:16 EDT
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