Measuring the Mass, SFR, and Ages of Galaxies Within the z=2.38 Filament

Abstract

We propose to obtain Spitzer images of the central 25x15 arcminutes of a z=2.38 filament of Lya-emitters. As the largest structure known above z=2, it represents a strong opportunity to test the predictions of hierarchical CDM models at high density. By combining IRAC and MIPS 24 micron observations, we will obtain ages, dust content, star formation rates, and masses for the Lya-emitters. We will also search the filament for the reddened star-forming galaxies which are predicted to cluster in higher density regions, such as the ultraluminous infrared galaxies (ULIGs). This field is also home to four (of 8 known) members of a recently discovered new class of object, the high-redshift extended Lya "blob''. These Lya blobs may directly show the formation of galaxies via the infall of intracluster gas or the outflow of enriched gas into the ICM, depending on their origin. Our IRAC and MIPS 24 micron observations can distinguish between the various models for the energy source that powers these objects.