NOAO >   Observing Info >   Approved Programs >   2013B-0358

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Proposal Information for 2013B-0358


PI: Larry Bradley, Space Telescope Science Institute, lbradley@stsci.edu
Address: Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218, USA

CoI: Renske Smit, Leiden University
CoI: Rychard Bouwens, Leiden University
CoI: Dan Coe, Space Telescope Science Institute
CoI: Marc Postman, Space Telescope Science Institute
CoI: Anton Koekemoer, Space Telescope Science Institute
CoI: Ivo Labbe, Leiden University
CoI: Piero Rosati, European Southern Observatory

Title: Combining Spectroscopy with Deep IRAC Observations to Obtain Accurate Mass Measurements for a Sample of Bright z~6.4-7.2 Lyman Break Galaxy Candidates in the CLASH Survey

Abstract: Understanding the early stellar mass growth of galaxies at z\gtrsim6 is very challenging for two reasons. First, the sources are inherently extremely faint. Second, recent observations indicate that essentially all estimates of galaxy masses at z\gtrsim5 are biased due to considerable contamination to the IRAC flux measurements from nebular emission lines. Here we propose to address both issues using a unique sample and strategy. We select highly-magnified candidates identified behind lensing clusters from the CLASH program in a narrow redshift range z~6.6-7.0. Here the strongest emission lines are isolated to only one IRAC filter ([3.6]), while the adjacent filter ([4.5]) is free of emission lines. We propose to use LRIS to determine their exact redshifts, which then allows us to place empirical constraints on the nebular emission contamination, opening the door to more accurate estimates of stellar mass. With a small sample of highly magnified, spectroscopically-confirmed z~6.6-7.0 galaxies, we can obtain the most robust sSFR measurement at z~7 yet available. The observed prevalence of Ly(alpha) emission in our sample can also be used to evaluate the ionization state of the universe.


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