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arXiv · 2111.01173

New spectroscopic confirmations of Lyman-$\alpha$ emitters at z $\sim$ 7 from the LAGER survey

Santosh Harish·Isak G. B. Wold·Sangeeta Malhotra·James Rhoads·Weida Hu·Junxian Wang·Zhen-ya Zheng·L. Felipe Barrientos·Jorge González-López·Lucia A. Perez·Ali Ahmad Khostovan·Leopoldo Infante·Chunyan Jiang·Cristóbal Moya-Sierralta·John Pharo·Francisco Valdes·Huan Yang
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Abstract

We report spectroscopic confirmations of 15 Lyman-alpha galaxies at $z\sim7$, implying a spectroscopic confirmation rate of $\sim$80% on candidates selected from LAGER (Lyman-Alpha Galaxies in the Epoch of Reionization), which is the largest (24 deg$^2$) survey aimed at finding Lyman-alpha emitters (LAEs) at $z\sim7$ using deep narrow-band imaging from DECam at CTIO. LAEs at high-redshifts are sensitive probes of cosmic reionization and narrow-band imaging is a robust and effective method for selecting a large number of LAEs. In this work, we present results from the spectroscopic follow-up of LAE candidates in two LAGER fields, COSMOS and WIDE-12, using observations from Keck/LRIS. We report the successful detection of Ly$\alpha$ emission in 15 candidates (11 in COSMOS and 4 in WIDE-12 fields). Three of these in COSMOS have matching confirmations from a previous LAGER spectroscopic follow-up and are part of the overdense region, LAGER-$z7$OD1. Additionally, two candidates that were not detected in the LRIS observations have prior spectroscopic confirmations from Magellan. Including these, we obtain a spectroscopic confirmation success rate of $\sim$$80$% for LAGER LAE candidates. Apart from Ly$\alpha$, we do not detect any other UV nebular lines in our LRIS spectra; however, we estimate a 2$\sigma$ upper limit for the ratio of NV/Ly$\alpha$, $f_{NV}/f_{Ly\alpha} \lesssim 0.27$, which implies that ionizing emission from these sources is mostly dominated by star formation. Including confirmations from this work, a total of 33 LAE sources from LAGER are now spectroscopically confirmed. LAGER has more than doubled the sample of spectroscopically confirmed LAE sources at $z\sim7$.

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Santosh Harish, Isak G. B. Wold, Sangeeta Malhotra, James Rhoads, Weida Hu, Junxian Wang, Zhen-ya Zheng, L. Felipe Barrientos, Jorge González-López, Lucia A. Perez, Ali Ahmad Khostovan, Leopoldo Infante, Chunyan Jiang, Cristóbal Moya-Sierralta, John Pharo, Francisco Valdes, Huan Yang. 2021-11-01. New spectroscopic confirmations of Lyman-$\alpha$ emitters at z $\sim$ 7 from the LAGER survey. https://doi.org/10.3847/1538-4357/ac7cf1

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