Nebular Emission with BPASS v2.2.1
BPASS generates the expected spectral energy distributions from stellar populations with known age and properties. It does not explicitly include nebular emission components. For this, reprocessing through a radiative transfer code such as Cloudy is required.
Cloudy is a complex code with a great many free parameters. We are not experts on its use and cannot guarantee that any set of input parameters will lead to physically realistic output parameters. We are happy to receive feedback on the following files.
Nonetheless, due to frequent requests, we make available a set of Cloudy-processed BPASS files as follows:
A nebular gas cloud with log(nH/cm-3)=2.3 and spherical geometry has been irradiated by BPASS spectra of known age and stellar metallicity, with a cloudy configuration as given at bottom of the page. All spectra are drawn from BPASS v.2.2.1, include binaries, and use imf135_300. We probe ionization parameters from logU = -1.0 to -4.0, and calculate models with the effects of interstellar grains "on" or "off". Separate Cloudy runs are required at each age step.
Outputs:
Available outputs are as follows:
Tar files of Cloudy-processed BPASS continuum and emission line outputs (see key in readme and below). Note that these are large tar files (labelled run_v10a.tar.gz etc).
Note that Cloudy renormalises its input spectra so output line luminosities are not reliably related to the normalisation of the stellar spectrum. To address this, we also provide reprocessed outputs renormalised to match BPASS mass/luminosity inputs. Line emission has been inserted with a single-angstrom width at its rest wavelength and these spectra should be smoothed to match spectral resolution of observations.
BPASS-formatted SED+line files (cloudyspec_outputs.tar.gz, 212 MB tar file)
Luminosities and Equivalent Widths for key emission lines (BPASS_v2.2_lines.zip, 337 kB zip file; readme_summaryfiles.txt)
Please cite the v2.2 paper (Stanway & Eldridge 2018) and the BPASS webpage)
Cloudy Configuration
Electron density: 200 cm-3
ionization parameters, logU=[-1.0,-1.5,-2.0,-2.5,-3.0,-3.5,-4.0]
grains : on or off
Standard BPASS metallicity compositions (all abundances scale relative to Solar)
sphere (spherical geometry)
covering factor 1.0 linear
iterate to convergence
stop temperature 100K (stopping conditions)
stop efrac -2
All other parameters set to default.
File label key:
Files are labeled as "_v10a", "_v11g" etc where the version numbers relate to ionization parameter and grains as below:
ver logden covfrac grains logU Z
10a 2.3 1.0 Y -1.0 zem5-0.40 (bin)
10b 2.3 1.0 Y -1.5 zem5-0.40 (bin)
10c 2.3 1.0 Y -2.0 zem5-0.40 (bin)
10d 2.3 1.0 Y -2.5 zem5-0.40 (bin)
10e 2.3 1.0 Y -3.0 zem5-0.40 (bin)
10f 2.3 1.0 Y -3.5 zem5-0.40 (bin)
10g 2.3 1.0 Y -4.0 zem5-0.40 (bin)
version 11a-g are identical but not including dust grain depletion.