NOAO >   Observing Info >   Approved Programs >   2018A-0371

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Program Information for 2018A-0371


PI: Sangeeta Malhotra, Arizona State U., sangeeta.malhotra@asu.edu
Address: School of Earth and Space Exploration, PO Box 871404, Tempe, AZ 85287-1404 USA

CoI: Zhenya Zheng, SHAO
CoI: James Rhoads, Arizona State U.
CoI: Junxian Wang, University of Science & Technology of China
CoI: Alistair Walker, CTIO
CoI: Leopoldo Infante, Pontificia Universidad Catolica de Chile
CoI: Linhua Jiang, Peking University
CoI: Chunyan Jiang, SHAO
CoI: Weida Hu, University of Science & Technology of China
CoI: Pascale Hibon, ESO
CoI: Huan Yang, LCO
CoI: Tianxing Jiang, Arizona State U.
CoI: John Pharo, Arizona State U.

Title: LAGER: Lyman Alpha Galaxies in the Epoch of Reionization (LAEs at z ~ 7 with DECam)

Abstract: The resonant properties of lya photons provide powerful tests of reionization via the statistical analysis of lya galaxies. While hundreds of LAEs have been efficiently detected with deep narrowband surveys up to $z$ = 6.6, they are largely missing at $zgtrsim$ 7. Is the decline of lya galaxies at $zgtrsim$ 7 due to neutral intergalactic medium (IGM), or a decline in CCD sensitivities at 1 micron, or a change in intrinsic properties of lya galaxies? To answer these questions, we are taking the definitive narrowband LAE survey project at $zsim$ 7 --- ``Lyman Alpha Galaxies in the Epoch of Reionization (LAGER).'' This survey exploits DECam's uniquely large FOV and QE in the near-infrared, as well as a custom narrowband filter at 9640AA built for DECam. By testing the apparent decline in the characteristic luminosity of 23 lya galaxies found in the central 1.4$^circtimes$1.4$^circ$ LAGER-COSMOS field, which is the largest lya galaxy sample at $zsim$ 7 to date, we have constrained a neutral hydrogen fraction of the integalactic medium (IGM) of $sim$40-60% at $zsim$7 (Zheng et al. 2017). More interestingly, we have found an excess of ultra luminous lya galaxies indicating an ionized bubble. Here we propose to double the NB964 exposure in the LAGER-COSMOS field, and to analyze our deeper data in conjunction with new Subaru HSC ultradeep broad band images in our field. The doubled NB964 image would allow us to 1) search the faint satellite galaxies around the luminous ones for the ionized bubble hypothesis; 2) improve the constraints on the faint-end slope for an effort to the ionizing budget of reionization; and apply 3) the EW distribution statistics and 4) the clustering test for improved constraints on the reionization and galaxy evolution model.

Program Type: Standard/Extragalactic

Scheduled Nights:
Run 1 (2018A):  CT-4m/DECam -- 3n on Mar 05 - Mar 10 2018


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 >   2018A-0371

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