4.1.31. Refl: reflection modelΒΆ

This model was kindly provided by Piotr Zycki. The related programs in XSPEC are felipl and ferfschw. The first one gives the reflected continuum (i.e. pexrav/pexriv) plus the line with correct energy and intensity, the second one is the first one with the relativistic smearing added. Both are combined into the single refl model in SPEX.

It is a model of reflection from a constant density X-ray illuminated atmosphere. It computes the Compton-reflected continuum (Magdziarz & Zdziarski, 1995); and the iron K alpha line (Zycki & Czerny, 1994), as described in Zicky et al. (1999). In addition, it can be convolved with a relativistic diskline model (for Schwarzschild geometry).

Chemical elements taken into account in this model are H, He, C, N, O, Ne, Mg, Si, S and Fe. The standard abundances are taken from Morrison & McCammon (1983).

The incoming spectrum is characterized by:

N_i(E) = A E^{-\Gamma}\exp \left[ -E/E_c \right],

where E is the photon energy in keV, N_i(E) the number of photons per per second per keV, \Gamma is the photon index and E_c a cut-off energy. The normalisation A is in units of 10^{44} photons \mathrm{s}^{-1} \mathrm{keV}^{-1} at 1 keV, just the same as in the standard power law model. The total spectrum N(E) is then given by

N(E) = N_i(E) + s R(E),

where R(E) is the reflected spectrum and s is a scaling factor.

The parameters of the model are:

norm : Normalisation A of the power law.
gamm : The photon index \Gamma of the ionising spectrum.
ecut : The cut-off energy (keV) of the ionising spectrum. If no cut-off is desired, take this parameter zero (and keep it frozen!).
pow : If pow=1, the incoming power law is added to the spectrum (default); if pow=0, only the reflected spectrum is given.
disk : If disk=1, the spectrum will be convolved with an accretion disk profile (default); if disk=0, this is not done.
fgr : Full general relativity used (default, for fgr=1).
t : Temperature of the reflector (disk) in keV.
xi : Ionisation parameter \xi=L/nr^2 in the usual (c.g.s. based) units of 10^{-9} W m.
abun : The abundance of all metals excluding H and He, in solar units
feab : The iron abundance with respect to the other metals
cosi : The cosine of the inclination angle of the disk. \cos i=0 (i=\pi/2) corresponds to edge-on
scal : Scale s for reflection. For an isotropic source above the disk s=1. This value corresponds to seeing equal contributions from the reflected and direct spectra.
q : Emissivity index for the accretion disk; default value -3 (the emissivity scales with r^{+q} at large radii, so q=-3 means r^-3. Note the sign difference with the Laor model.
r1 : Inner radius of the disk in units of GM/c^2. Default: 10.
r2 : Outer radius of the disk in units of GM/c^2. Default: 10^4.

Recommended citation: Magdziarz & Zdziarski (1995) and Zicky et al. (1999)