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Published October 21, 2015 | Published + Submitted
Journal Article Open

Deriving star formation histories from photometry using energy balance spectral energy distribution modelling


Panchromatic spectral energy distribution fitting is a critical tool for determining the physical properties of distant galaxies, such as their stellar mass and star formation rate. One widely used method is the publicly available MAGPHYS code. We build on our previous analysis by presenting some modifications which enable MAGPHYS to automatically estimate galaxy star formation histories (SFHs), including uncertainties, based on ultraviolet to far-infrared photometry. We use state-of-the art synthetic photometry derived by performing three-dimensional dust radiative transfer on hydrodynamic simulations of isolated disc and merging galaxies to test how well the modified MAGPHYS is able to recover SFHs under idealized conditions, where the true SFH is known. We find that while the SFH of the model with the best fit to the synthetic photometry is a poor representation of the true SFH (showing large variations with the line of sight to the galaxy and spurious bursts of star formation), median-likelihood SFHs generated by marginalizing over the default MAGPHYS libraries produce robust estimates of the smoothly varying isolated disc simulation SFHs. This preference for the median-likelihood SFH is quantitatively underlined by our estimates of χ2_(SFH) (analogous to the χ2 goodness-of-fit estimator) and ΔM/M (the integrated absolute mass discrepancy between the model and true SFH) that strongly prefer the median-likelihood SFHs over those that best fit the UV-to-far-IR photometry. In contrast, we are unable to derive a good estimate of the SFH for the merger simulations (either best fit or median likelihood) despite being able to obtain a reasonable fit to the simulated photometry, likely because the analytic SFHs with bursts superposed in the standard MAGPHYS library are insufficiently general/realistic.

Additional Information

© 2015 The Royal Astronomical Society. Accepted 2015 July 27. Received 2015 July 27. In original form 2015 June 9. First published online August 25, 2015. The authors would like to thank the reviewer, Elisabete da Cunha, for an insightful report that improved the quality of this paper. We also wish to thank Charlie Conroy, Phil Hopkins and Ben Johnson for useful discussions. DJBS and CCH would like to acknowledge a financial award from the Santander Universities partnership scheme. CCH is grateful to the Gordon and Betty Moore Foundation for financial support and the University of Hertfordshire for hospitality. DJBS would like the thank the Theoretical AstroPhysics Including Relativity and Cosmology (TAPIR) group at Caltech for their hospitality. This research has made use of NASA's Astrophysics Data System Bibliographic Services. Moore Prize Postdoctoral in Theoretical Astrophysics.

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Submitted - 1507.07554v1.pdf

Published - 1597.full.pdf


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August 20, 2023
August 20, 2023