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:

$$\frac{dY}{dT} = \left\{ \begin{array}{ll} 0 & {\rm if\quad} T \le... ...} < T < T_{max} \\ 0 & {\rm if\quad} T_{max} \leq < T \\ \end{array}\right\}$$

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

HEASARC Home | Observatories | Archive | Calibration | Software | Tools | Students/Teachers/Public

Last modified: Friday, 23-Aug-2024 13:20:40 EDT

HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.