NOAO >   Observing Info >   Approved Programs >   2012A-0373

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Proposal Information for 2012A-0373


PI: Chun Ly, Space Telescope Science Institute, chunly@stsci.edu
Address: 3700 San Martin Drive, Baltimore, MD 21218-2410, USA

CoI: Matthew A. Malkan, University of California, Los Angeles
CoI: Kentaro Motohara, University of Tokyo
CoI: Masao Hayashi, National Astronomical Observatory of Japan
CoI: Nobunari Kashikawa, National Astronomical Observatory of Japan
CoI: Kazuhiro Shimasaku, University of Tokyo
CoI: Tohru Nagao, Kyoto University

Title: Galaxy Evolution with a Complete Photometric Redshift Census at z~2- 3

Abstract: We are using our unique set of deep imaging in 25 wavebands to obtain the first \it complete census of the entire z=2-3 galaxy population in the large volume of the Subaru Deep Field. Instead of traditional color-selection methods, which we have shown are seriously incomplete and biased (Ly et al. 2011), we are obtaining accurate and reliable photometric redshifts for all types of galaxies, down to one- fifth of M_\star. However, the one remaining hole in our wavelength coverage is the H-band, that pinpoints the Balmer and 4000Abreaks at z~2-3. These are crucial for deriving accurate redshifts, and for modeling the spectral energy distribution (SED). We therefore request one NEWFIRM night to complete our 1500\AA-2.2(micron) SED coverage. These observations will yield an estimated sample of at least 5,000 galaxies with reliable photometric redshift across the critical cosmic epoch when the star-formation rate (SFR) density peaked and most galaxies were built. The fitting of their detailed multi-band SEDs will allow us to measure their basic astrophysical properties: stellar mass, SFR, age and extinction. Broad wavelength coverage is required to break the age/extinction degeneracy in these fits. Compared with our earlier imaging efforts that suffered from poor observing conditions, these H- band data will be 1.5 magnitudes deeper, expanding our earlier sample by an order of magnitude. The results from these measurements will be compared to those obtained for lower redshift populations, allowing us to measure galaxy evolution over the past eleven billion years.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2012A-0373

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