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THE SPECTRAL ENERGY DISTRIBUTION OF POST-STARBURST GALAXIES IN THE NEWFIRM MEDIUM-BAND SURVEY: A LOW CONTRIBUTION FROM TP-AGB STARS

Journal Article · · Astrophysical Journal Letters
;  [1];  [2]; ; ; ;  [3]; ;  [4];  [5];  [6];  [7]
  1. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
  2. Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
  3. Department of Astronomy, Yale University, New Haven, CT 06520 (United States)
  4. Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands)
  5. UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
  6. Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)
  7. Department of Physics and Astronomy, The University of Kansas, Lawrence, KS 66045 (United States)
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 {approx_lt} z {approx_lt} 2.0, from which we construct a well-sampled composite spectral energy distribution (SED) over the range 1200-40000 A. The SED is well fit by the Bruzual and 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 A, 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 {approx}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.
OSTI ID:
21452758
Journal Information:
Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 722; ISSN 2041-8205
Country of Publication:
United States
Language:
English