NOAO >   Observing Info >   Approved Programs >   2001A-0139

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Proposal Information for 2001A-0139


PI: James Rhoads, Space Telescope Science Institute, rhoads@stsci.edu
Address: 3700 San Martin Drive, Baltimore, MD 21218, USA

CoI: Sangeeta Malhotra, Johns Hopkins University
CoI: Arjun Dey, Kitt Peak National Observatory

Title: Catching them Young: Galaxies at z=6.6

Abstract: Recent discoveries of high redshift galaxies and quasars have pushed back the age of galaxy formation to z>5. These include discoveries of galaxies at z > 5, and of evolved, dusty objects with old populations at what are now considered modest redshifts of 3.5-4.5. Since searches for Ly-(alpha) emitting galaxies were predicted to find young galaxies in the throes of the first stages of star-formation, before they chemically enrich the surrounding material to produce dust, it is vital to push back the searches of Ly-(alpha) emitters to earlier cosmic times. To quantify evolution and galaxy formation between z=4.5 and 6.6, we propose a large area (one Mosaic field: 36' \appx 75 Mpc) search for galaxies with strong Ly-(alpha) line emission at redshift 6.6, using a clean window free of night sky lines. The number density of emitters from this survey will be compared to those found with our previous, successful, survey at z=4.5 and 5.7 to study the evolution of galaxies with strong Ly-(alpha) line. This sample will also facilitate comparison of the relative numbers of Ly-(alpha) line emitters having little continuum with galaxies found by the dropout method which have strong continuum and varying Ly-(alpha) line strength. The relative number of these two populations in the 3 redshifts windows (z=4.5, 5.7 and 6.6) will give a measure of the evolution of populations of galaxies. The Mosaic camera on the Mayall telescope optimizes the area and depth of the survey. The large sky area covered allows us to (a) integrate deep to obtain many candidates efficiently (b) get a statistically useful sample to compare with our z=4.5 sample and measure evolution of this class of youngest galaxies. We will thus identify a statistically and scientifically useful sample of z~ 6.6 galaxies, \it all of which will break the current galaxy redshift record.


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