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| Paper: |
The Stellar Masses and Star Formation Histories of Galaxies at z ∼ 6: Constraints from Spitzer GOODS Observations |
| Volume: |
380, At the Edge of the Universe: Latest Results from the Deepest Astronomical Surveys |
| Page: |
35 |
| Authors: |
Yan, H.; Dickinson, M.; Giavalisco, M.; Stern, D.; Eisenhardt, P.R.M.; Ferguson, H.C. |
| Abstract: |
Using the deep Spitzer Infrared Array Camera (IRAC) observations of the Great Observatories Origins Deep Survey (GOODS), we study the stellar masses and star formation histories (SFH) of galaxies at z ≈ 6. The IRAC instrument provides the best opportunity to estimate the stellar masses of galaxies at these redshifts because it samples their rest-frame optical fluxes, which are less prone to dust extinction and are more sensitive to the light from longer-lived stars. Our study is based on the i775-band dropout sample selected from the GOODS southern and northern fields (~ 330 arcmin2 in total), several of which already have spectroscopic confirmations. We present the analysis for both the IRAC-detected and IRAC-non-detected i775-dropouts. The former ones have typical stellar masses of ~ 1010M⊙ and typical ages of a couple of hundred million years, while the latter ones are much younger and are typically less massive by a factor of ten. The existence of high-mass galaxies at z ≈ 6 can be explained by at least one set of N-body simulations of the hierarchical paradigm. Based on our mass estimates, we derive a lower limit to the global stellar mass density at z ≈ 6. We also investigate the implication of our results for reionzation, and find that the progenitors of the galaxies comparable to those in our sample, even in the most optimized (probably unrealistic) scenario, cannot sustain the reionization for a period longer than ~ 2 million years. |
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