Browsing by Author "Rhoads, James "

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    LAGER Lyα Luminosity Function at z ∼ 7: Implications for Reionization
    (2022) Wold, Isak G. B. ; Malhotra, Sangeeta ; Rhoads, James ; Wang, Junxian ; Hu, Weida ; Perez, Lucia A. ; Zheng, Zhen-Ya ; Khostovan, Ali Ahmad ; Walker, Alistair R. ; Barrientos, L. Felipe ; González-López, Jorge ; Harish, Santosh ; Infante, Leopoldo ; Jiang, Chunyan ; Pharo, John ; Moya-Sierralta, Cristóbal ; Bauer, Franz E. ; Galaz, Gaspar ; Valdes, Francisco ; Yang, Huan
    We present a new measurement of the Ly alpha luminosity function (LF) at redshift z = 6.9, finding moderate evolution from z = 5.7 that is consistent with a fully or largely ionized z similar to 7 intergalactic medium. Our result is based on four fields of the LAGER (Lyman Alpha Galaxies in the Epoch of Reionization) project. Our survey volume of 6.1 x 10(6) Mpc(3) is double that of the next largest z similar to 7 survey. We combine two new LAGER fields (WIDE12 and GAMA15A) with two previously reported LAGER fields (COSMOS and CDFS). In the new fields, we identify N = 95 new z = 6.9 Ly alpha emitter (LAEs) candidates, characterize our survey's completeness and reliability, and compute Ly alpha LFs. The best-fit Schechter LF parameters for all four LAGER fields are in good general agreement. Two fields (COSMOS and WIDE12) show evidence for a bright-end excess above the Schechter function fit. We find that the Ly alpha luminosity density declines at the same rate as the UV continuum LF from z = 5.7 to 6.9. This is consistent with an intergalactic medium that was fully ionized as early as redshift z similar to 7 or with a volume-averaged neutral hydrogen fraction of x (H I) < 0.33 at 1 sigma.