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Paper: GOODS Spitzer IRAC Observations of High-z Galaxies
Volume: 381, The Second Annual Spitzer Science Center Conference: Infrared Diagnostics of Galaxy Evolution
Page: 317
Authors: Yan, H.; Dickinson, M.; Giavalisco, M.; Stern, D.; Eisenhardt, P.R.M.; Ferguson, H.C.; the GOODS Team
Abstract: The Great Observatory Origins Deep Survey (GOODS) Spitzer Legacy Program has obtained ∼ 23.2 hours of IRAC observations in the HDF-N and the CDF-S (∼ 330 arcmin2 in total), among which a sub-area of ∼ 50 arcmin2 in the HDF-N has been observed to a depth of ∼ 72 hours. Utilizing these deep IRAC data, we study the stellar masses and star formation histories of galaxies at z ≈ 6. While some of the i-band dropouts selected by the GOODS ACS observations are detected by these IRAC observations, some of them are not. We find that the i775-dropouts in the IRAC-detected sample typically have stellar masses of ∼ 1010M and ages of a few hundred million years old, consistent with our earlier results based on a smaller sample in the HUDF. On the other hand, the i-dropouts in the IRAC-invisible sample are significantly younger and less massive. Using these results, we derive the lower limit of the global stellar density at z ≈ 6, and find that at least 0.2–1.1% of the stellar mass in our local universe has been locked in stars by z ≈ 6.
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