Contains calculations and fitting codes (ISIS table models and XSPEC models) from Corrales et. al. (2016)
http://arxiv.org/abs/1602.01100
To download, use git to create an ismdust folder:
git clone https://github.com/eblur/ismdust.git ismdust
The following models are provided
- ISMdust
- OlivineAbs
- ISMdust_sca (ISIS only)
- ISMdust_abs (ISIS only)
- FeLedge (ISIS only)
This model provides the extinction (= absorption + scattering) properties for a power law distribution of dust grains using the optical properties for dust provided in Draine (2003).
sil_md : dust mass column for Silicate in units of 1.e-4
default = 0.6
gra_md : dust mass column for Graphite in units of 1.e-4
default = 0.4
redshift : redshift of the obscuring dust (XSPEC only)
default = 0.0
The default mixture of 60% / 40% silicate / graphite is described in Corrales et al. (2016). Please cite this paper if you use this model.
A model for olivine absorption that uses the silicate absorption model from ISMdust with the Rogantini et al. (2018) cross-section for the Fe K edge incorporated.
olv_md : dust mass column for Olivine grains in units of 1.e-4
default = 1.0
redshift : redshift of the obscuring dust (XSPEC only)
default = 0.0
Please cite both Corrales et al. (2016) and Rogantini et al. (2018) if you use this model.
Each model returns exp(-tau md), where tau is the path-integrated
absorption, scattering, or extinction optical depth and md is the
dust mass column in units of 10^-4 g cm^-2.
To estimate the appropriate dust mass column for a given ISM column (NH), one must choose a dust-to-gas mass ratio. For for the Milky Way ISM, this value is typically ~0.01.
For example, NH = 10^22 cm^-2 corresponds to NH * m_p (proton mass) * 0.01 =
1.67e-4 g cm^-2. One can then set, for example, the md_sil
parameter in ISMdust to 1.67.
Enter the ismdust directory and start XSPEC
XSPEC12> initpackage ismdust lmodel_ismdust.dat .
XSPEC12> exit
Finally, set an environment variable to point to location of ismdust, e.g.
export ISMDUSTROOT=/path/to/ismdust/
Now, when you want to load the ISMDUST model in XSPEC, load the correct library. The following example loads ismdust and then applies the extinction model to a power law component:
XSPEC12> lmod ismdust $::env(ISMDUSTROOT)
XSPEC12> mo ismdust*pow
Note: You can omit the $::env(ISMDUSTROOT) portion if you have the LMODDIR
environment variable set to the location where ISMdust is installed.
Try the test file to make sure it's working.
XSPEC12> @test.xcm
Follow the instructions above to set your ISMDUSTROOT environment variable
(and LMODDIR, if you choose).
Now install the local model
XSPEC12> initpackage olivineabs lmodel_olivineabs.dat .
To load the model in XSPEC:
XSPEC12> lmod olivineabs $::env(ISMDUSTROOT)
XSPEC12> mo olivineabs*pow
Try the test file to make sure it's working.
XSPEC12> @test_olivine.xcm
Add a line to your .isisrc file
add_to_isis_load_path("/path/to/ismdust/ismdust_isis");
Set an environment variable (same way you would for the XSPEC model)
export ISMDUSTROOT=/path/to/ismdust/
When you want to invoke the model, use the require function in ISIS to load ismdust
isis> require("ismdust");
To set up the model extinction model with a power law continuum, for example, do:
isis> require("ismdust");
isis> fit_fun("ismdust(1) * powerlaw(1)");
For absorption component only
isis> require("ismdust");
isis> fit_fun("ismdust_abs(1) * powerlaw(1)");
For scattering component only
isis> require("ismdust");
isis> fit_fun("ismdust_sca(1) * powerlaw(1)");
See ismdust_isis/test_ismdust.sl
Use the same set up instructions as above.
To run the model with a power law continuum, for example, do:
isis> require("olivineabs");
isis> fit_fun("olivineabs(1) * powerlaw(1)");
See also ismdust_isis/test_olivine.sl
Set an environment variable to point to the location of the Fe-L edge templates:
export FEPATH=/path/to/ismdust/ismdust_isis/
To invoke the model:
isis> require("FeLedge");
isis> fit_fun("FeLedge(1) * powerlaw(1)");