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Spectral Simulations

Mock galaxy spectra have been generated for all WAVES sources in Theoretical Astrophysical Observatory (TAO) simulations using the SpecGen tool. This process produces model spectra for a broad range of physical parameters using high signal-to-noise observed SDSS spectra in the GAMA regions and then matches to our simulated survey.

Each SDSS spectrum has its continuum and lines fit by a combination of multiple 4th-order polynomials and gaussian line shapes respectively. A model is generated based on these fits which produces a purely parametric model spectra, retaining emission line ratios, continuum shapes and line equivalent widths, but having essentially infinite signal-to-noise and resolution. This model template can then be edited to fit the desired parameters of our simulated survey.

The GAMA derived properties of stellar masses (from ugrizJHK spectral fitting), star-formation rate (from extinction corrected Halpha emission lines) and rest-frame g-i colour are retained for each SDSS source, and model galaxies are split into star-forming and passive systems based on their emission line strengths.

TAO simulated galaxies are then subdivided also into star-forming (SFR>0) and passive (SFR=0) based on their semi-analytic properties. For star-forming galaxies TAO simulated galaxies are matched to star-forming SDSS model spectra based on specific SFR and colour, while passive systems are matched to passive SDSS model spectra based on stellar mass and colour alone.

Given the parametric nature of these model spectra, they can be scaled to the absolute magnitude (i-band), redshift and emission line velocity widths of the TAO simulated source. Model spectra are output for each source over the 4MOST wavelength range and resolution (over-sampled by a factor of 10). The figure displays a single simulated spectrum, with SDSS filter bands overlaid. Simulated spectra recover the g-band,r-band and i-band TAO magnitudes to <0.1mag.

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