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.
- 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.