NOAO >   Observing Info >   Approved Programs >   2013B-0528

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Proposal Information for 2013B-0528


PI: James E. Rhoads, Arizona State University, James.Rhoads@asu.edu
Address: School of Earth and Space Exploration, PO Box 871404, Tempe, AZ 85287-1404, USA

CoI: Sangeeta Malhotra, Arizona State University
CoI: Ronald Probst, NOAO
CoI: Rob Swaters, NOAO
CoI: Pascale Hibon, Gemini Observatory
CoI: Bahram Mobasher, University of California, Riverside
CoI: Vithal S. Tilvi, Texas A& M University
CoI: Sylvain Veilleux, University of Maryland
CoI: Junxian Wang, University of Science and Technology of China
CoI: Steven Finkelstein, University of Texas
CoI: Zhenya Zheng, Arizona State University

Title: The Cosmic Deep And Wide Narrowband (Cosmic DAWN) Survey

Abstract: We propose a definitive test for the neutral gas fraction near the epoch of reionization using a survey of Lyman-alpha emitters at z=7.7. The redshift of reionization, its speed, and its homogeneity are unknowns, with the Gunn-Peterson tests probing the end of reionization at z > 6, while WMAP suggests z_re=11. Ly-alpha galaxies provide a powerful tool to probe the central phase of reionization with neutral fractions of gas ~ 50% because the Lyman-alpha photons scatter resonantly. The observed Lyman-alpha luminosity function (LF) should then show a substantial decline. We pioneered the use of Ly-alpha emitters to show that the IGM is more than 50% ionized at z=6.5 (Malhotra & Rhoads 2004). We now propose 40 nights of deep narrowband imaging in 4 fields to find \lya line emitters. The custom filter is designed, tested, and performing well in NEWFIRM. This survey is 40 times more powerful than the state of the art in this field. We expect to find 40 Lyman-alpha emitters, and 10 in each field, if the IGM is ionized at z=7.7. With four fields, we guard against cosmic variance and inhomogenieties in reionization. Even if the IGM at z=7.7 is 50% neutral we will find 5 sources, which lie in an OH free wavelength and are good for spectroscopic followup. Presently, there are 0 confirmed Lyman-alpha emitters at z > 7.3.


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