NOAO >   Observing Info >   Approved Programs >   2014A-0395

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Proposal Information for 2014A-0395


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: Fuyan Bian, Mt Stromlo Observatory, Astralian National University
CoI: Yujin Yang, Argelander-Institut fuer Astronomie
CoI: Ann Zabludoff, Steward Observatory, University of Arizona
CoI: Zhenya Zheng, Arizona State University

Title: Probing the Large Scale Overdensity with Quasar Groups at the Peak Era of Galaxy Formation

Abstract: Extremely massive halos, where the most biased tracers of large- scale structure cluster, are potent constraints on models of structure formation. To find the most overdense regions of the early universe, past studies have employed tracers such as high-z radio galaxies, sub-mm galaxies, or extended Ly(alpha) sources, as well as redshift surveys for Lyman-break galaxies. Yet the utility of these markers is limited by a relatively small survey volume and/or strong selection biases. We propose a different approach: using newly-discovered, extremely rare clusters of multiple QSOs to find the precursors of rich clusters of galaxies today. With the SDSSIII-BOSS survey, we have discovered three unique QSO groups at z=2.32+/-0.02, each with a remarkable 6-7 QSOs clustered within ~ 0.09 deg^2 (~30 co-Mpc). These fields are ~15-20\times denser in QSOs than average. To confirm these massive overdensities, and test how well QSOs and Ly(alpha) emitters (LAEs) trace one another, we propose to carry out deep narrowband (NB403)+ broadband (B band) imaging using the KPNO 4-m+MOSAIC camera. Our custom narrowband filter \sl NB403 ((lambda)_c=4030\AA, FWHM=45\AA) and MOSAIC's large FOV are ideally suited for this program. Although our observations in 2013A were severely hampered by poor weather, our preliminary data still indicate the confirmation of a significant LAE overdensity in one QSO group field at the bright-end.


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