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wdem, vwdem, vvwdem, bwdem, bwwdem, bvvwdem: plasma emission, multi-temperature with power-law distribution of emission measure.

A multi-temperature collisional-ionization equilibrium plasma emission model. The emission measure distribution is a powerlaw:

$\displaystyle \frac{dY}{dT} = \left\{ \begin{array}{ll} 0 & {\rm if\quad} T \le... ...} < T < T_{max} \\ 0 & {\rm if\quad} T_{max} \leq < T \\ \end{array}\right\} $
where $Y$ is the emission measure and $c$ is chosen so that the total emission measure equals the normalization parameter (Kaastra et al. 2004).

The switch parameter determines whether the spectrum is calculated by running the mekal code, by interpolating on a pre-calculated mekal table, using the AtomDB data, or the SPEX data. The final two options are now preferred. See the cie model for further information and options.

For the wdem version, the abundance ratios are set by the abund command. The vwdem variant allows the user to define abundances for the more common elements while vvwdem has parameters for abundances of all elements up to Zn. See the documentation on the apec model for further information.

Velocity broadening can only be used with switch=2 or switch=3.

The parameters for wdem are:

par1 Maximum temperature for power-law emission measure distribution
par2 Ratio of minimum to maximum temperature ( $\beta = T_min/T_max$)
par3 Inverse slope ($p = 1/\alpha$)
par3 nH (cm$^{-3}$). Fixed at 1 for most applications.
par4 abundance relative to Solar
par5 redshift z
par6 switch (0 = calculate using MEKAL model; 1 = interpolate using MEKAL model; 2 = interpolate using AtomDB data, 3 = interpolate using SPEX data)
norm Normalization

For the vwdem variant the parameters are:

par1 Maximum temperature for power-law emission measure distribution
par2 Ratio of minimum to maximum temperature ( $\beta = T_min/T_max$)
par3 Inverse slope ($p = 1/\alpha$)
par4 nH (cm$^{-3}$)
par5–18 abundance for He, C, N, O, Ne, Na, Mg, Al, Si, S,Ar, Ca, Fe, Ni wrt Solar (defined by the abund command)
par19 redshift z
par20 switch (0 = calculate using MEKAL model; 1 = interpolate using MEKAL model; 2 = interpolate using AtomDB data, 3 = interpolate using SPEX data)
norm Normalization

For the vvwdem variant the parameters are:

par1 Maximum temperature for power-law emission measure distribution
par2 Ratio of minimum to maximum temperature ( $\beta = T_min/T_max$)
par3 Inverse slope ($p = 1/\alpha$)
par4 nH (cm$^{-3}$)
par5–34 abundance for H to Zn wrt Solar (defined by the abund command)
par35 redshift z
par36 switch (0 = calculate using MEKAL model; 1 = interpolate using MEKAL model; 2 = interpolate using AtomDB data, 3 = interpolate using SPEX data)
norm Normalization

The parameters for the bwdem variant with a parameter for velocity broadening are:

par1 Maximum temperature for power-law emission measure distribution
par2 Ratio of minimum to maximum temperature ( $\beta = T_min/T_max$)
par3 Inverse slope ($p = 1/\alpha$)
par3 nH (cm$^{-3}$). Fixed at 1 for most applications.
par4 abundance relative to Solar
par5 redshift z
par6 Gaussian sigma for velocity broadening (km/s) (switch=2 or 3 only)
par7 switch (0 = calculate using MEKAL model; 1 = interpolate using MEKAL model; 2 = interpolate using AtomDB data, 3 = interpolate using SPEX data)
norm Normalization

For the bvwdem variant with a parameter for velocity broadenin gthe parameters are:

par1 Maximum temperature for power-law emission measure distribution
par2 Ratio of minimum to maximum temperature ( $\beta = T_min/T_max$)
par3 Inverse slope ($p = 1/\alpha$)
par4 nH (cm$^{-3}$)
par5–18 abundance for He, C, N, O, Ne, Na, Mg, Al, Si, S,Ar, Ca, Fe, Ni wrt Solar (defined by the abund command)
par19 redshift z
par20 Gaussian sigma for velocity broadening (km/s) (switch=2 or 3 only)
par21 switch (0 = calculate using MEKAL model; 1 = interpolate using MEKAL model; 2 = interpolate using AtomDB data, 3 = interpolate using SPEX data)
norm Normalization

For the vvwdem variant with a parameter for velocity broadenin the parameters are:

par1 Maximum temperature for power-law emission measure distribution
par2 Ratio of minimum to maximum temperature ( $\beta = T_min/T_max$)
par3 Inverse slope ($p = 1/\alpha$)
par4 nH (cm$^{-3}$)
par5–34 abundance for H to Zn wrt Solar (defined by the abund command)
par35 redshift z
par36 Gaussian sigma for velocity broadening (km/s) (switch=2 or 3 only)
par37 switch (0 = calculate using MEKAL model; 1 = interpolate using MEKAL model; 2 = interpolate using AtomDB data, 3 = interpolate using SPEX data)
norm Normalization

next up previous contents
Next: vagauss, zvagauss: gaussian line Up: Additive Model Components Previous: tapec, vtapec, vvtapec: APEC   Contents