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J. E. Rhoads (STScI), S. Malhotra (JHU), A. Dey (NOAO), D. Stern (JPL), H. Spinrad (Berkeley), B. Jannuzi (NOAO)
The discovery of a few truly primordial galaxies--- that is, chemically primitive systems undergoing their first generation of star formation--- will be a key step in our efforts to understand how galaxies form and evolve. The Large Area Lyman Alpha survey is an ongoing effort to identify a large sample of young galaxies at high redshifts (z=4.5 and z=5.7) using the strong Lyman alpha emission line expected in such objects. We have achieved sensitivity comparable to the deepest published surveys (~2 \times 10-17 erg/cm2/s) over a volume ~100 times larger (~106 comoving Mpc3). Early spectroscopic followup at Keck has confirmed our ability to identify high redshift galaxies using our narrow band images. We find that the Lyman alpha emitters contribute substantially to both the galaxy census and the total star formation rate at z=4.5. Future observations of these objects will allow us to look for evidence of galactic winds, which could eject heavy elements into the intergalactic medium; old stars, which would have to have formed at redshifts z>4.5; dust, which would imply chemical enrichment; and spatial substructure, which could rule out some galaxy formation scenarios. We will also study evolution in the numbers and properties of these galaxies up to z=5.7 with existing data. Planned extensions of this work to still higher redshift will allow us to probe the epoch of reionization, before which the universe was opaque to Lyman alpha photons.
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The author(s) of this abstract have provided an email address for comments about the abstract: rhoads@stsci.edu