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Published 2008 | Published
Book Section - Chapter Open

GOODS Spitzer IRAC Observations of High-z Galaxies


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 arcmin^2 in total), among which a sub-area of ~50 arcmin^2 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 i_(775)-dropouts in the IRAC-detected sample typically have stellar masses of ~10^(10)M_⊙ 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.

Additional Information

© 2008 Astronomical Society of the Pacific. We thank the other members of the GOODS team who have contributed to the success of the observations and data analysis. Support for this work, part of the Spitzer Space Telescope Legacy Science Program, was provided by NASA through Contract Number 1224666 issued by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407.

Attached Files

Published - Yan2008p8804Second_Annual_Spitzer_Science_Center_Conference_Infrared_Diagnostics_Of_Galaxy_Evolution.pdf



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August 19, 2023
January 12, 2024