CPWABS model
CPWABS is a constant pressure warm absorber model for XSPEC.
Files
Different high/low spin and high/low accretion rate variants parametrizing accretion disk emission are supplied in separate files. Files naming scheme is like "cpwabs_?s?md.fits". Suffixes "hs" or "ls" are for high (0.9) or low (0.1) spin; "hmd" or "lmd" are for high (0.1) or low (0.001) accretion rate.
Usage
The model provides absorption spectra computed with Titan code (Dumont, Abrassart Collin, 2000). The conntinuum part of the spectra is reprocessed ionizing continuum with absorption line created at the line of sight. Full radiative transfer with ALI method is computed (not just escape probabilities). Simulations are done for constant pressure regime and line spectral profiles are computed.
This is model derived from photoionization simulations. As a consequence we parametrize both ionizing continuum and the gas at the line of sight. Ionizing continuum is parametrized as a disk continuum + power-law. Power-law is described by the photon index Gamma in X-ray band. The allowed range for Gamma is provided between 1.4 and 3.2, with a step 0.2. The gas slab illuminated by defined continuum is parametrized by column density given in logarithm with the allowed range of values between 20 and 23.6 computed with a step 0.1. Gas initial local density at the face of the cloud was assumed to be 10^8 cm^-3. It is necessery to to provide ionization parameter xi at the face of the cloud, which is computed in logarithm in the range 3-5 with a step value equals 1. The last parameter which must be provided is redshift of the source. The order of parameters is like that: Gamma, log_xi, log_NH, z.
Example
data 1:1 Mkn509_MERGED_R1.pi
model phabs*atable{cpwabs_hslmd.fits}
0.0283295 -0.001 0 0 100000 1e+06
2 0.2 1.4 1.4 3.2 3.2
4 1 3 3 5 5
22 0.1 20 20 23.6 23.6
0.034397 -0.001 0 0 5 5
1.14132e-18 0.01 0 0 1e+20 1e+24
fit
Output:
========================================================================
Model phabs*atable{cpwabs_hslmd.fits} Source No.: 1 Active/On
Model Model Component Parameter Unit Value
par comp
1 1 phabs nH 10^22 2.83295E-02 frozen
2 2 cpwabs Gamma 2.28268 +/- 4.96147E-03
3 2 cpwabs xi 4.03775 +/- 2.62699E-02
4 2 cpwabs log_NH 22.7886 +/- 1.26533E-02
5 2 cpwabs z 3.43970E-02 frozen
6 2 cpwabs norm 4.00022E-21 +/- 6.60621E-22
________________________________________________________________________
Fit statistic : Chi-Squared = 8186.75 using 3010 PHA bins.
Test statistic : Chi-Squared = 8186.75 using 3010 PHA bins.
Reduced chi-squared = 2.72347 for 3006 degrees of freedom
Null hypothesis probability = 0.000000e+00
