Stellar Population Spectra

Class providing spectral energy distributions (SEDs) for simple stellar populations (SSPs)—the luminosity per unit frequency (in \(L_\odot\) Hz\(^{-1}\)) of a coeval population of stars as a function of age, metallicity, and wavelength. These SEDs are convolved with the star formation history to produce the integrated galaxy SED, which is compared to observed photometry or spectra. Implementations typically wrap stellar isochrone libraries and atmosphere grids such as FSPS, BC03, or BPASS.

Default implementation: stellarPopulationSpectraFSPS

Methods

luminosity → double precision

Return the luminosity (in units of \(L_\odot\) Hz\(^{-1}\)) for a stellar population, composition abundances, of the given age (in Gyr), at the specified wavelength (in Angstroms).

  • type (abundances), intent(in ) :: abundancesStellar

  • double precision , intent(in ) :: age , wavelength

  • integer , intent( out), optional :: status

tabulation → void

Return a tabulation of ages and metallicities at which stellar spectra should be tabulated.

  • integer , intent( out) :: agesCount, metallicitiesCount

  • double precision, allocatable, dimension(:), intent( out) :: ages , metallicity

wavelengths → void

Return a tabulation of wavelengths at which stellar spectra are defined.

  • integer , intent( out) :: wavelengthsCount

  • double precision, allocatable, dimension(:), intent( out) :: wavelengths

wavelengthInterval → double precision

At a given wavelength, return the wavelength interval in the tabulation of wavelength for which stellar spectra are defined.

  • double precision, intent(in ) :: wavelength

stellarPopulationSpectraFile

A stellar population spectra class which computes spectra via interpolation in a tabulation read from file. This should be an HDF5 file with the following structure:

ages                     Dataset {ageCount}
metallicities            Dataset {metallicityCount}
spectra                  Dataset {metallicityCount, ageCount, metallicityCount}
wavelengths              Dataset {wavelengthCount}

where the datasets contain the tabulated ages (in Gyr), metallicities (logarithmic, relative to Solar), wavelengths (in AA) and spectra (in \(L_\odot\) Hz\(^{-1}\)).

Scripts to convert the data provided by Maraston (2005) and Bruzual and Charlot (2003) into Galacticus’s format are provided in the scripts/ssps folder.

Methods

  • readFile — Read the named power spectrum file.

Parameters

  • [forceZeroMetallicity] (default .false.) — Force the use of zero metallicity (or lowest metallicity available) for all stellar populations.

  • [fileName] — The path to the HDF5 file containing the tabulated stellar population spectra, with datasets for ages (Gyr), metallicities (log Solar), wavelengths (AA), and spectra (\(L_\odot\,\mathrm{Hz}^{-1}\)); see the scripts/ssps folder for conversion scripts.

  • [fileName] — The name of the file which contains fit coefficients for the time per tree fitting function.

  • [fileName] (default inputPath(pathTypeDataStatic)//'stellarAstrophysics/stellarPropertiesCompilationStandard.xml') — The name of the XML file from which to read stellar properties (ejected masses, yields, etc.).

  • [fileName] (default inputPath(pathTypeDataStatic)//'stellarAstrophysics/Stellar_Tracks_Padova.hdf5') — The name of the HDF5 file from which to read stellar tracks.

  • [fileName] — The name of the file from which to read intergalactic medium state data.

  • [fileName] — The name of the file from which to read intergalactic background light properties.

  • [fileName] — The name of a file from which to read tabulated spectra of accretion disks.

  • [fileName] — The name of the file from which to read a tabulated transfer function.

stellarPopulationSpectraFSPS

A stellar population spectra class utilizing the FSPS package (Conroy et al., 2009). If necessary, the FSPS code will be downloaded, patched and compiled and run to generate spectra. These tabulations are then stored to file for later re-use. The file name used is datasets/dynamic/stellarPopulations/simpleStellarPopulationsFSPS:v<version>_<descriptor>.hdf5 where \(<\)version\(>\) is the FSPS version used, and \(<\)descriptor\(>\) is an MD5 hash descriptor of the selected stellar population.

(Default implementation)

Parameters

  • [forceZeroMetallicity] (default .false.) — Force the use of zero metallicity (or lowest metallicity available) for all stellar populations.