Galaxies 09: Assembly, Gas Content and Star Formation History of Galaxies
Chris Hayward
Harvard-Smithsonian Center for Astrophysics
Calibrating and Testing Star-Formation Rate Indicators Using Simulations
We analyze N-body/smoothed-particle hydrodynamics simulations of isolated and merging galaxies, performed using \textit{Gadget-2} (Springel 2005), with the 3-D adaptive grid, polychromatic Monte Carlo radiative transfer code \textit{Sunrise} (Jonsson, Groves, and Cox 2009, Jonsson 2006). We apply commonly used UV, optical, and IR star-formation rate (SFR) indicators to the spectral energy distributions of the simulated galaxies in order to determine how well the SFR indicators recover the known SFR in the simulations. The models upon which the SFR indicator calibrations are based must necessarily make simple assumptions about physical properties of the galaxies, e.g., the star formation history (SFH), whereas all such properties in the simulations are known and are closer to those of actual galaxies. This benefit of the simulations enables us to test and compare SFR indicators in a way that is complimentary to observational studies. We use our approach to provide more sophisticated calibrations of the SFR indicators and to characterize systematic errors and uncertainties caused by SFH, dust and source geometry, viewing angle, contamination from active galactic nuclei and old stellar populations, and assumed initial mass function, stellar population synthesis model, and dust model. We focus on how well the SFR indicators, which are primarily tested observationally for local galaxies, apply to simulations of high-redshift galaxies.
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