IAU00000
Presentation type requested: POSTER
EVOLUTION IN THE COLORS OF LYMAN-BREAK GALAXIES FROM Z~4 TO Z~3 IN THE GREAT OBSERVATORIES ORIGINS DEEP SURVEY
Casey Papovich
Steward Observatory
The integrated colors of distant galaxies provide a means for interpreting the properties of their stellar content. Here, we study the rest-frame UV-to-optical colors of B-dropout galaxies at z~4 using HST/ACS and VLT/ISAAC data from the Great Observatories Origins Deep Survey. The rest-frame m(UV)-B versus B color-magnitude diagram for the z~4 galaxies is slightly bluer, but otherwise consistent with that of U-dropout galaxies at z~3. We find that although the co-moving luminosity density at rest-frame UV wavelengths is comparable, the luminosity density at rest-frame optical wavelengths increases by ~40% from z~4 to z~3. The evolution in the global luminosity density of the UV-bright galaxy population corresponds to an average star-formation history with a star-formation rate that is constant or increasing over this redshift range. By comparing the observations to models with simple star-formation histories, we suggest that the evolution of the luminosity density corresponds to an increase in the stellar-mass density of >50%, and we describe how these constraints will be greatly improved with forthcoming observations from SIRTF.
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro; Lotz, Jennifer; Madau, Piero; Idzi, Rafal; Kretchmer, Claudia; Moustakas, Leonidas A.; de Mello, Duilia F.; Gardner, Jonathan P.; Rieke, Marcia J.; Somerville, Rachel S.; Stern, Daniel.
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