NOAO >   Observing Info >   Approved Programs >   2012A-0574

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Proposal Information for 2012A-0574


PI: Casey Papovich, Texas A&M University, papovich@physics.tamu.edu
Address: 4242 TAMU, College Station, TX 77843-4242, USA

CoI: Karl Glazebrook, Swinburne University of Technology
CoI: Glenn Kacprzak, Swinburne University of Technology
CoI: Ivo LabbÈ, Leiden Observatory
CoI: Lee Spitler, Swinburne University of Technology
CoI: Kim-Vy Tran, Texas A&M University
CoI: Vithal Tilvi, Texas A&M University

Title: H-alpha Narrow Band Imaging of a Forming Cluster at z=2.2

Abstract: We propose Gemini/NIRI narrow-band (NB) imaging to measrue H-alpha emission in galaxies associated with a z=2.2 forming cluster. This cluster was discovered in our deep survey, z-FourGE, which uses custom medium-band near-IR filters with Magellan/FourStar. z-FourGE delivers accurate photometric redshifts with dz/(1+z) 1-2% for galaxies at z>1.5. Theory predicts that the star-formation rate per galaxy stellar mass (the specific SFR) evolves differently in low- and high-density regions. This cluster is observed during an epoch when the galaxies are still forming their stars and the cluster is collapsing. We propose to image the cluster deeply with four narrow band (R 40-60) filters, spanning 2.04-2.18 micron and tracing H-alpha emission at z=2.1-2.3. In one hour per filter the data will be sensitive to the H-alpha emission with line fluxes of 3.4 x 10^-18 erg/s/cm^2 (or EW=10 Ang for our survey limit of K(AB)=23 mag). This science is unique to Gemini: No other 8m-class telescope has an IR imager with extisting NB filters for this science. Our goals are (1) to map the redshift distribution of galaxies associated with this forming cluster (2) to measure accurate specific SFRs as a function of galaxy density during the epoch when cluster galaxies and clusters are forming.


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-0574

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