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arXiv · 1008.4357

The Spectral Energy Distribution of Post-Starburst Galaxies in the NEWFIRM Medium-Band Survey: A Low Contribution from TP-AGB Stars

Mariska Kriek·Ivo Labbe·Charlie Conroy·Katherine Whitaker·Pieter van Dokkum·Gabriel Brammer·Marijn Franx·Garth Illingworth·Danilo Marchesini·Adam Muzzin·Ryan Quadri·Gregory Rudnick
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Abstract

Stellar population synthesis (SPS) models are a key ingredient of many galaxy evolution studies. Unfortunately, the models are still poorly calibrated for certain stellar evolution stages. Of particular concern is the treatment of the thermally-pulsing asymptotic giant branch (TP-AGB) phase, as different implementations lead to systematic differences in derived galaxy properties. Post-starburst galaxies are a promising calibration sample, as TP-AGB stars are thought to be most prominently visible during this phase. Here, we use post-starburst galaxies in the NEWFIRM medium-band survey to assess different SPS models. The available photometry allows the selection of a homogeneous and well-defined sample of 62 post-starburst galaxies at 0.7<z<2.0, from which we construct a well-sampled composite spectral energy distribution (SED) over the range 1200-40 000 Angstrom. The SED is well-fit by the Bruzual & Charlot SPS models, while the Maraston models do not reproduce the rest-frame optical and near-infrared parts of the SED simultaneously. When the fitting is restricted to lambda < 6000 Angstrom, the Maraston models overpredict the near-infrared luminosity, implying that these models give too much weight to TP-AGB stars. Using the flexible SPS models by Conroy et al, and assuming solar metallicity, we find that the contribution of TP-AGB stars to the integrated SED is a factor of ~3 lower than predicted by the latest Padova TP-AGB models. Whether this is due to lower bolometric luminosities, shorter lifetimes, and/or heavy dust obscuration of TP-AGB stars remains to be addressed. Altogether, our data demand a low contribution from TP-AGB stars to the SED of post-starburst galaxies.

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Mariska Kriek, Ivo Labbe, Charlie Conroy, Katherine Whitaker, Pieter van Dokkum, Gabriel Brammer, Marijn Franx, Garth Illingworth, Danilo Marchesini, Adam Muzzin, Ryan Quadri, Gregory Rudnick. 2010-12-16. The Spectral Energy Distribution of Post-Starburst Galaxies in the NEWFIRM Medium-Band Survey: A Low Contribution from TP-AGB Stars. https://doi.org/10.1088/2041-8205%2F722%2F1%2Fl64

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