Gabriel Brammer
Yale University
 

"Red galaxies at z>3.5: is this an important epoch for feedback mechanisms in massive galaxies?"
 

Recent multi-wavelength cosmological surveys that include deep near- infrared photometry have identified a population of galaxies at z~2.5 with red rest-frame colors. These galaxies dominate the mass density of the universe at this redshift.  I present a new NIR selection based on the H-K color to extend the study of red galaxies to z>3. While as many as half of red galaxies at z~2.3 have very low star formation rates, the H-K galaxies have significant rest-frame UV emission suggesting that they are still actively forming stars. Because the H-K galaxies are likely progenitors of red galaxies at lower redshift, they represent a promising laboratory for studying feedback mechanisms that quench star formation in massive galaxies.  I will discuss ongoing observations with Gemini-GMOS and with the new NIR camera, NEWFIRM, at Kitt Peak that will enable the study of massive galaxies at z>2 with unprecedented detail.