NOAO >   Observing Info >   Approved Programs >   2012A-0507

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Proposal Information for 2012A-0507


PI: Sylvain Veilleux, University of Maryland, veilleux@astro.umd.edu
Address: Department of Astronomy, Stadium Drive, College Park, Maryland 20742, USA

CoI: Hannah Krug, University of Maryland
CoI: Sangeeta Malhotra, Arizona State University
CoI: James Rhoads, Arizona State University
CoI: Vithal Tilvi, Texas A&M University
CoI: Pascale Hibon, Gemini Observatory

Title: Spectroscopic Follow-up of z ~ 8 Ly(alpha) Emitters in the COSMOS Field

Abstract: Ly(alpha) emitters are a useful probe of the reionization epoch, as in a neutral intergalactic medium (IGM), resonantly scattered Ly(alpha) photons do not transmit to the observer easily. When the IGM is primarily neutral, the observed Ly(alpha) luminosity function (LF) should thus decline significantly. We have used the Ly(alpha) LF to show that the IGM is \gtrsim 50% ionized at z=6.5, which corresponds nicely with the Gunn-Peterson trough lower limit of x_HI \gtrsim 1% at z~ 6.3. As we expect a continuous reionization process, direct observational probes of higher redshifts - e.g., the z=7.7 Ly(alpha) window - will be quite useful for constraining reionization. \textitHere we request one night for spectroscopic follow-up on GNIRS of the two brightest z=7.7 Ly(alpha) emitter candidates identified in the COSMOS field; these data will be an integral part of H. Krug's Ph.D. thesis. If successful, these objects would be among the very few galaxies at z>7 with spectroscopically confirmed redshifts. The discovery of galaxies stemming from the first generation, as these targets should be, would be quite a coup for observational cosmology and for Gemini Observatory. Non-detection of Ly(alpha) emitters in multiple fields would imply that reionization is not yet complete at z=7.7. The spectroscopic confirmation of Ly(alpha) galaxies at z=7.7 is critical for determining LF evolution and z_reion.


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NOAO >   Observing Info >   Approved Programs >   2012A-0507

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