XSPEC models which estimate the X-ray absorption in the IGM to a specified redshift

Compile using the initpackage command and load using the lmod command.

igmabs - X-ray absorption in the WHIM

R.L.C. Starling, R. Willingale, N.R. Tanvir, A.E. Scott, K. Wiersema, P.T. O’Brien, A.J. Levan and G.C. Stewart, 2013, MNRAS

E. Behar, S. Dado, A. Dar, A. Laor, 2011, ApJ, 734, 26

The model calculates the X-ray absorption expected from the WHIM for a source at a specified redshift. The WHIM is modelled as a simple uniform medium with constant temperature and ionisation state.

Abundances to be assumed for the WHIM can be set using the XSPEC abund command prior to using the model.

Parameters and typical values

n0        density 10-7 atoms cm-3                        1.7 (x10^-7 cm-3)
PhoIndex  photon index of photo-ionizing spectrum        1.4
logtk     temperature logK                               5 (T=10^5 K)
logxi     log ionisation state 4*pi*flux/n0 ergs cm s-1  log10(2.6e-6/1.2/n0)
z         redshift to source

Subroutine - xsigmabs()

lyfabs - X-ray absorption in the Lyman forest

R.L.C. Starling, R. Willingale, N.R. Tanvir, A.E. Scott, K. Wiersema, P.T. O’Brien, A.J. Levan and G.C. Stewart, 2013, MNRAS

P. Petitjean, J.K. Webb, M. Rauch, R.F. Carswell, K. Lanzetta, 1993, MNRAS, 262, 499

C. Peroux, R.G. McMahon, L.J. Storrie-Lombardi, M.J. Irwin, 2003, MNRAS, 346, 1103

C. Peroux, M. Dessauges-Zavadsky, S. D’Odorico, T.-S. Kim, R.G. McMahon, 2007, MNRAS, 382, 177

The model calculates the X-ray absorption expected from the Lyman forest for a source at a specified redshift. The Lyman forest is modelled as cold gas with a density and metalicity which vary with redshift.

density = n0*(z+1)^dind

metalicity log10[X/H] = m0+z*mind ([x/H] = 10^(m0+z*mind)

Solar abundances can be set using the XSPEC abund command prior to using the model. The abundances are modified during the calculation but reset to the original solar values on return. The m0 parameter determines the abundances for the Lyman forest with respect to solar at z=0.

Parameters and typical values

n0 	 density atoms 10-9 cm-3 at z=0     8 (x10-9 cm-3)
dind     index of density wrt (z+1)         2.4 (density increases with z)
m0       log10[X/H] metalicity at z=0       -0.4 (abundances at z=0 0.4 solar)
mind     index of metalicity wrt z          -0.42 (metalicity decreases with z)
z        redshift to source

Subroutine - xslyfabs()