reflionx — reflection from an atmosphere ionized by illuminating X-rays

The emergent ("reflected") spectrum is calculated for an optically-thick atmosphere of constant density (such as the surface of an accretion disk) illuminated by X-rays with a power-law spectrum. The illumination has a high-energy exponential cutoff with e-folding energy fixed at 300 keV. Non-LTE calculations provide temperature and ionization structures for the gas that are consistent with the local radiation fields. In addition to fully-ionized species, the following ions are included in the calculations: C III–VI, N III–VII, O III–VIII, Ne III–X, Mg III–XII, Si IV–XIV, S IV–XVI, and Fe VI–XXVI.

The reflionx models improve on the previous reflion models described by Ross & Fabian 2005 (MNRAS, 358, 211) in two ways:

  • In the previous models, the illuminating spectrum covered the entire calculated range from 1 eV to 1 MeV. For the steepest spectra , this meant that most of the energy was in very soft photons, which may not have been reasonable physically and which made the "ionization parameter" a poor measure of the actual ionizing power of the illumination. In the reflionx models, the illumination is confined to "X-rays," with an abrupt low-energy cutoff at E = 0.1 keV. The transfer of reprocessed radiation with E < 0.1 keV is treated in the calculations but is not included in the tabulated models.

  • For more accurate interpolation within XSPEC, a finer grid is used for both the ionization parameter and the power-law photon index. The reflionx table includes 1800 individual models.

Download reflionx.mod (2.6 MB)

Model parameters:
Fe/solar (range 0.1 to 20.0)
Abundance of iron relative to solar value. Abundances of other elements are fixed at solar values (Morrison & McCammon 1983, ApJ, 270, 119).

Gamma (range 1.4 to 3.3)
Photon index for illuminating power-law spectrum above 0.1 keV.

Xi (range 10 to 10,000 erg cm/s)
Ionization parameter,

where F is the total illuminating flux and nH is the hydrogen number density.

Redshift to be applied to reflected spectrum.

Normalization applied to reflected spectrum.