NOAO >   Observing Info >   Approved Programs >   2014B-0293

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Proposal Information for 2014B-0293


PI: Zheng Cai, Steward Observatory, University of Arizona, caiz@email.arizona.edu
Address: Physics Department, 1118E, 4TH STREET, Tucson, AZ 85721, USA

CoI: Xiaohui Fan, Steward Observatory, University of Arizona
CoI: Brenda Frye, Steward Observatory, University of Arizona
CoI: Richard Green, Steward Observatory, University of Arizona
CoI: Ian McGreer, Steward Observatory, University of Arizona
CoI: Yujin Yang, Argelander-Institut fuer Astronomie
CoI: Ann Zabludoff, Steward Observatory

Title: Mapping the Most Massive Overdensity Through HI: KPNO-4m/MOSAIC Observations of a Galaxy Overdensity at z=2.3

Abstract: By examining the absorption spectra of ~140,000 sight lines provided by the SDSS-III quasar survey at z=2-4, we have identified the most extreme Ly(alpha) absorber overdensities. Our survey extends over a volume of 1Gpc^3 to search the most massive galaxy structures at z=2.32+/-0.03 which can be probed by our custom narrowband filter. These overdensities, which also include high concentration of quasars at the same redshift, are likely to represent the most biased regions in the universe at the peak of galaxy formation (z=2-3). Our simulations suggest a strong correlation between the 1-D high optical depth Ly(alpha) absorbers, which arise from the IGM, and true 3-D mass overdensities over scales of 10-30 h^-1 Mpc. We now have discovered two systems at z=2.3 with the largest 1-D absorber overdensities at 20 h^-1 Mpc found to date at z>2. We propose here to carry out deep narrowband (NB403)+ broadband (Bw) imaging of these systems with the KPNO-4m/MOSAIC. These observations will confirm and characterize the galaxy overdensities associated with the groups of intergalactic Ly(alpha) absorbers, and thus are crucial to reveal the star formation activity in what may turn out to be the most overdense galaxy environments at z>2.


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