%0 Generic %1 zheng2017first %A Zheng, Zhen-Ya %A Wang, Junxian %A Rhoads, James %A Infante, Leopoldo %A Malhotra, Sangeeta %A Hu, Weida %A Walker, Alistair R. %A Jiang, Linhua %A Jiang, Chunyan %A Hibon, Pascale %A Gonzalez, Alicia %A Kong, Xu %A Zheng, Xianzhong %A Galaz, Gaspar %A Barrientos, Felipe L. %D 2017 %K Lya emitters epoch reionization %T First results from the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) survey: Cosmological Reionization at z ~ 7 %U http://arxiv.org/abs/1703.02985 %X We present the first results from the ongoing LAGER project (Lyman Alpha Galaxies in the Epoch of Reionization), which is the largest narrowband survey for $z\sim$ 7 galaxies to date. Using a specially built narrowband filter NB964 for the superb large-area Dark-Energy Camera (DECam) on the NOAO/CTIO 4m Blanco telescope, LAGER has collected 34 hours NB964 narrowband imaging data in the 3 deg$^2$ COSMOS field. We have identified 27 Lyman Alpha Emitter (LAE) candidates at $z=$ 6.9 in the central 2-deg$^2$ region, where DECam and public COSMOS multi-band images exist. The resulting luminosity function can be described as a Schechter function modified by a significant excess at the bright end (4 galaxies with L$_Ly\alpha\sim$ 10$^43.4\pm0.2$ erg s$^-1$). The number density at L$_Ly\alpha\sim$ 10$^43.4\pm0.2$ erg s$^-1$ is little changed from $z= 6.6$, while at fainter $L_Ly\alpha$ it is substantially reduced. Overall, we see a fourfold reduction in Ly$\alpha$ luminosity density from $z= 5.7$ to $6.9$. Combined with a more modest evolution of the continuum UV luminosity density, this suggests a factor of $3$ suppression of Ly$\alpha$ by radiative transfer through the $z7$ intergalactic medium (IGM). It indicates an IGM neutral fraction $x_HI$ $\sim$ 0.4-0.6 (assuming Ly$\alpha$ velocity offsets of 100-200 km s$^-1$). The changing shape of the Ly$\alpha$ luminosity function between $złesssim 6.6$ and $z=6.9$ supports the hypothesis of ionized bubbles in a patchy reionization at $z\sim$ 7.

@misc{zheng2017first, abstract = {We present the first results from the ongoing LAGER project (Lyman Alpha Galaxies in the Epoch of Reionization), which is the largest narrowband survey for $z\sim$ 7 galaxies to date. Using a specially built narrowband filter NB964 for the superb large-area Dark-Energy Camera (DECam) on the NOAO/CTIO 4m Blanco telescope, LAGER has collected 34 hours NB964 narrowband imaging data in the 3 deg$^2$ COSMOS field. We have identified 27 Lyman Alpha Emitter (LAE) candidates at $z=$ 6.9 in the central 2-deg$^2$ region, where DECam and public COSMOS multi-band images exist. The resulting luminosity function can be described as a Schechter function modified by a significant excess at the bright end (4 galaxies with L$_{Ly\alpha}\sim$ 10$^{43.4\pm0.2}$ erg s$^{-1}$). The number density at L$_{Ly\alpha}\sim$ 10$^{43.4\pm0.2}$ erg s$^{-1}$ is little changed from $z= 6.6$, while at fainter $L_{Ly\alpha}$ it is substantially reduced. Overall, we see a fourfold reduction in Ly$\alpha$ luminosity density from $z= 5.7$ to $6.9$. Combined with a more modest evolution of the continuum UV luminosity density, this suggests a factor of $\sim 3$ suppression of Ly$\alpha$ by radiative transfer through the $z\sim 7$ intergalactic medium (IGM). It indicates an IGM neutral fraction $x_{HI}$ $\sim$ 0.4-0.6 (assuming Ly$\alpha$ velocity offsets of 100-200 km s$^{-1}$). The changing shape of the Ly$\alpha$ luminosity function between $z\lesssim 6.6$ and $z=6.9$ supports the hypothesis of ionized bubbles in a patchy reionization at $z\sim$ 7.}, added-at = {2017-03-10T12:24:02.000+0100}, author = {Zheng, Zhen-Ya and Wang, Junxian and Rhoads, James and Infante, Leopoldo and Malhotra, Sangeeta and Hu, Weida and Walker, Alistair R. and Jiang, Linhua and Jiang, Chunyan and Hibon, Pascale and Gonzalez, Alicia and Kong, Xu and Zheng, Xianzhong and Galaz, Gaspar and Barrientos, Felipe L.}, biburl = {https://www.bibsonomy.org/bibtex/2b46ccc5b550bd56792394eda8b1746ec/miki}, description = {[1703.02985] First results from the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) survey: Cosmological Reionization at z ~ 7}, interhash = {17c9bc60446966342f618880502f5aa2}, intrahash = {b46ccc5b550bd56792394eda8b1746ec}, keywords = {Lya emitters epoch reionization}, note = {cite arxiv:1703.02985Comment: 6 pages, 3 figures, submitted to ApJ Letters}, timestamp = {2017-03-10T12:24:02.000+0100}, title = {First results from the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) survey: Cosmological Reionization at z ~ 7}, url = {http://arxiv.org/abs/1703.02985}, year = 2017 }