4.6. SED interpolation

Phosphoros provides a tool to create new SEDs through a linear interpolation of two SED templates present in the input library. This tool can help users to fill regions of the colors space that are undersampled.

Users have to select two reference SEDs for the interpolation and to choose the number of new SEDs to be generated. The interpolation is performed along the wavelength axis and the new SEDs will be uniformly distributed between the two reference SEDs. If the reference SEDs have a different sampling in wavelengths, the finest SED sampling is used to resample the other SED. If the two SEDs cover different wavelength range, interpolation is computed only in the common range and new SEDs are set to zero outside.

4.6.1. SED interpolation with GUI

In Configuration-->AuxiliaryData-->SEDs sub-panel, users can click on the Create Interpolated SEDs button, and a pop-up window opens (see Fig. 4.4). After selecting two SEDs of the input library, users must provide the number of new SEDs to be created. Clicking on the Add SED, a new input SED can be added and used for interpolation.

The directory where interpolated SEDs are stored is specified in the Save in a new Folder with name tab. The directory is expected to be new, otherwise, it will be cleaned before storing the new SEDs. Input SEDs used for the interpolation can be also included in the directory by selecting the Copy selected SEDs in the output folder tab.

The name used to store a new SED is explanatory of how interpolation is computed: in the example of Fig. 4.4, 2 new SEDs are generated from Ell1_A_0.sed and Ell2_A_0.sed, and a new one from Ell2_A_0.sed and Ell3_A_0.sed; their names will be:

> 1:3_Ell1_A_0_+_2:3_Ell2_A_0.sed
> 2:3_Ell1_A_0_+_1:3_Ell2_A_0.sed
> 1:2_Ell2_A_0_+_1:2_Ell3_A_0.sed

Fig. 4.4 Panel to create interpolated SEDs

4.6.2. SED interpolation with CLI

SED interpolation can be performed in the CLI using the InterpolateSED (or IS) action.

An example of configuration file is:

sed-dir=$PHOSPHOROS_ROOT/AuxiliaryData/SEDs/CosmosEll
seds=Ell1_A_0.sed,Ell2_A_0.sed,Ell3_A_0.sed
numbers=2,1
out-dir=<dir-name>
copy-sed=False

With the above configuration file, Phosphoros creates three new SEDs: two by interpolating the Ell1_A_0.sed and Ell2_A_0.sed SEDs, and one by interpolating the Ell2_A_0.sed and Ell3_A_0.sed SEDs. Output files are stored in the directory <dir-name> below AuxiliaryData/SEDs/CosmosEll (the location of the output directory is relative to the directory provided by --sed-dir), and named as shown in the previous sub-section. Input SEDs are not copied into the output directory.

Note

If physical parameters are found in SED file headers, common physical parameters are interpolated too. Set --interpolate-pp=False to avoid it.