mekal, vmekal: emission, hot diffuse gas (Mewe-Kaastra-Liedahl)
An emission spectrum from hot diffuse gas based on the model calculations of Mewe and Kaastra with Fe L calculations by Liedahl. The model includes line emissions from several elements. The switch parameter determines whether the mekal code will be run to calculate the model spectrum for each temperature or whether the model spectrum will be interpolated from a pre-calculated table. The former is slower but more accurate. Relative abundances are set by the abund command for the mekal model. The vmekal variant allows the user to set the individual abundances for the model.
par1 |
plasma temperature in keV |
par2 |
H density (cm-3) |
par3 |
Metal abundance (He fixed at cosmic). The elements included are C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, Ni. |
par4 |
(fixed) redshift |
Par5 |
0 calculate |
1 interpolate |
|
2 interpolate using APEC model |
|
norm |
where DA is the angular size distance to the source (cm), and ne , nH (cm-3) are the electron and hydrogen densities respectively. |
Parameters for the vmekal variant are:
par1 |
plasma temperature in keV |
par2 |
H density (cm-3) |
par3-par16 |
Abundances for He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, Ni wrt Solar (given by the Anders & Grevesse mixture) |
par17 |
(fixed) redshift |
par18 |
0 calculate |
1 interpolate |
|
2 interpolate using APEC model |
|
norm |
where DA is the angular size distance to the source (cm), and ne , nH (cm-3) are the electron and hydrogen densities respectively. |
The references for the MEKAL model are as follows :
Mewe, R., Gronenschild, E.H.B.M., and van den Oord, G.H.J. 1985,A&AS, 62, 197
Mewe, R., Lemen, J.R., and van den Oord, G.H.J. 1986, A&AS}, 65, 511
Kaastra, J.S. 1992, An X-Ray Spectral Code for Optically Thin Plasmas (Internal SRON-Leiden Report, updated version 2.0)
Liedahl, D.A., Osterheld, A.L., and Goldstein, W.H. 1995, ApJL, 438, 115
Similar acknowledgement may also be given for the adopted ionization balance:
Arnaud, M., and Rothenflug, M. 1985, A&AS, 60, 425
Arnaud, M., and Raymond, J. 1992, ApJ, 398, 394