Thursday, June 5, 2014

Stellar Population Synthesis Including Binary Stars

I'm making available a script which will convert the stellar population spectra from the BPASS project into Galacticus HDF5 format, so that they can be used in Galacticus calculations. Just drop the script into your Galacticus directory, run it, and it will download, unpack, and convert the BPASS data. You'll be left with two files (one for populations including only single stars, and another for populations including binaries) in the data/stellarPopulations/ directory that you can then use in Galacticus when computing galaxy luminosities.

Binaries can have a significant effect on galaxy colors (see the papers on the BPASS page for more details). For example, the following plot shows the distribution of u-z colors for galaxies at z=0 when computed using the FSPS stellar population code, and when using the BPASS code (with single and binary populations).

The galaxies with binary stars are offset bluewards by about 0.2 magnitudes. I wonder what effect this has on stellar mass estimates based on broad-band photometry..........?