Model for partial covering of partially ionised absorbing material.

NOTE: This model is now in the Xspec release and this page is superceded by the Xspec manual

This uses a grid of XSTAR photionised absorption models (calculated assuming a microturbulent velocity of 200km/s) for the absorption, then assumes that this only covers some fraction f of the source, while the remaining (1-f) of the spectrum is seen directly. This is the model used by Reeves et al (2008) 'On why the iron K-shell absorption in AGN is not the signature of the local warm-hot intergalactic medium', and may also be more generally applicable to the spectral complexity seen in Narrow Line Seyfert 1 AGN (Miller et al 2007, A&A, 463, 13).

This is a multiplicative model. The parameters are

par1 = column density in units of 1022 cm^-2
par2 = log(xi) where xi=L/nr^2
par3 = covering fraction f
par4 = redshift

To install this model download the source code (zxipcf.f), model datafile (zxipcf_mtable.fits), and the model parameter description file (zxipcf_lmodel.dat). zxipcf will look for its model datafile in the current directory or the directory specified in xspec by using xset ZXIPCF_DIR directory.

Questions and comments? Contact Chris Done: chris.done(at)

Keith Arnaud, Lab. for High Energy Astrophysics, NASA/Goddard Space Flight Center

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Last modified: Tuesday, 14-Feb-2023 16:42:04 EST

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