%0 Generic %1 ota2017constraint %A Ota, Kazuaki %A Iye, Masanori %A Kashikawa, Nobunari %A Konno, Akira %A Nakata, Fumiaki %A Totani, Tomonori %A Kobayashi, Masakazu A. R. %A Fudamoto, Yoshinobu %A Seko, Akifumi %A Toshikawa, Jun %A Ichikawa, Akie %A Shibuya, Takatoshi %A Onoue, Masafusa %D 2017 %K Lya igm reionization %T A New Constraint on Reionization by a Census of $z=7.0$ Ly$\alpha$ Emitters with a Deep and Large Sample to 0.3 $L^*$: Evolution of Ly$\alpha$ Luminosity Function and Equivalent Width at $z\sim6-7$ %U http://arxiv.org/abs/1703.02501 %X We conduct a census of 20 $z=7.0$ Ly$\alpha$ emitters (LAEs) detected in Subaru Deep Field (SDF) and Subaru XMM Deep Survey (SXDS) field to a Ly$\alpha$ luminosity limit $L(Ly\alpha) = 2.010^42$ erg s$^-1$ or $\sim 0.3$ $L^*_z=7$ in a volume $V=6.110^5$ Mpc$^3$ by our $80$ and 37 hrs of Subaru Telescope Suprime-Cam narrowband NB973 and reddest optical y-band imagings. We compare Ly$\alpha$ luminosity function (LF), rest frame UV LF, Ly$\alpha$ equivalent width (EW) distribution of $z=7.0$ LAEs to those of $z=5.7$, 6.6 and 7.3 LAEs from previous Suprime-Cam surveys to comparable limits. The Ly$\alpha$ LF significantly declines from $z=5.7$ to 7.0 at the bright to faint end and from $z=6.6$ to 7.0 at the faint end. It more significantly declines from $z=7.0$ to 7.3. Meanwhile, though the UV LF of LAEs does not evolve much at $z=5.7$-6.6, it modestly declines from $z=6.6$ to 7.0. Furthermore, in addition to the systematic decrease in Ly$\alpha$ EWs from $z=5.7$ to 6.6 previously found, we find that 2/3 of our $z=7.0$ LAEs detected in the UV continuum have lower EWs than those of $z=6.6$ LAEs. These results indicate that the Ly$\alpha$ LF acceleratingly decreases at $z>5.7$ as suggested by previous studies, and the decline of the UV LF at $z=6.6$-7.0 suggests that galaxy evolution contributes to the declines of the Ly$\alpha$ LF and EWs at this epoch. Comparison of our $z=7.0$ Ly$\alpha$ LF to the one predicted by a recent LAE evolution model further reveals that galaxy evolution alone cannot explain all the decline of the Ly$\alpha$ LF at $z=7.0$. If we attribute the discrepancy to Ly$\alpha$ attenuation by neutral hydrogen, the intergalactic medium transmission of Ly$\alpha$ photons at $z=7.0$ would be $0.6$-0.7. It is lower (higher) than the one at $z=6.6$ ($z=7.3$) derived by previous studies, suggesting that neutral fraction increases at $z > 6$.

@misc{ota2017constraint, abstract = {We conduct a census of 20 $z=7.0$ Ly$\alpha$ emitters (LAEs) detected in Subaru Deep Field (SDF) and Subaru XMM Deep Survey (SXDS) field to a Ly$\alpha$ luminosity limit $L({\rm Ly}\alpha) = 2.0\times 10^{42}$ erg s$^{-1}$ or $\sim 0.3$ $L^*_{z=7}$ in a volume $V=6.1\times 10^5$ Mpc$^3$ by our $\sim 80$ and 37 hrs of Subaru Telescope Suprime-Cam narrowband NB973 and reddest optical y-band imagings. We compare Ly$\alpha$ luminosity function (LF), rest frame UV LF, Ly$\alpha$ equivalent width (EW) distribution of $z=7.0$ LAEs to those of $z=5.7$, 6.6 and 7.3 LAEs from previous Suprime-Cam surveys to comparable limits. The Ly$\alpha$ LF significantly declines from $z=5.7$ to 7.0 at the bright to faint end and from $z=6.6$ to 7.0 at the faint end. It more significantly declines from $z=7.0$ to 7.3. Meanwhile, though the UV LF of LAEs does not evolve much at $z=5.7$-6.6, it modestly declines from $z=6.6$ to 7.0. Furthermore, in addition to the systematic decrease in Ly$\alpha$ EWs from $z=5.7$ to 6.6 previously found, we find that 2/3 of our $z=7.0$ LAEs detected in the UV continuum have lower EWs than those of $z=6.6$ LAEs. These results indicate that the Ly$\alpha$ LF acceleratingly decreases at $z>5.7$ as suggested by previous studies, and the decline of the UV LF at $z=6.6$-7.0 suggests that galaxy evolution contributes to the declines of the Ly$\alpha$ LF and EWs at this epoch. Comparison of our $z=7.0$ Ly$\alpha$ LF to the one predicted by a recent LAE evolution model further reveals that galaxy evolution alone cannot explain all the decline of the Ly$\alpha$ LF at $z=7.0$. If we attribute the discrepancy to Ly$\alpha$ attenuation by neutral hydrogen, the intergalactic medium transmission of Ly$\alpha$ photons at $z=7.0$ would be $\leq 0.6$-0.7. It is lower (higher) than the one at $z=6.6$ ($z=7.3$) derived by previous studies, suggesting that neutral fraction increases at $z > 6$.}, added-at = {2017-03-08T18:54:30.000+0100}, author = {Ota, Kazuaki and Iye, Masanori and Kashikawa, Nobunari and Konno, Akira and Nakata, Fumiaki and Totani, Tomonori and Kobayashi, Masakazu A. R. and Fudamoto, Yoshinobu and Seko, Akifumi and Toshikawa, Jun and Ichikawa, Akie and Shibuya, Takatoshi and Onoue, Masafusa}, biburl = {https://www.bibsonomy.org/bibtex/2f6b455af7c541faca94ab1225c70fadc/miki}, description = {[1703.02501] A New Constraint on Reionization by a Census of $z=7.0$ Ly$\alpha$ Emitters with a Deep and Large Sample to 0.3 $L^*$: Evolution of Ly$\alpha$ Luminosity Function and Equivalent Width at $z\sim6-7$}, interhash = {b3af749669a51c9d2a9f7b4d29e8bddd}, intrahash = {f6b455af7c541faca94ab1225c70fadc}, keywords = {Lya igm reionization}, note = {cite arxiv:1703.02501Comment: 36 Pages, 22 Figures, 10 Tables, Submitted to ApJ}, timestamp = {2017-03-08T18:54:30.000+0100}, title = {A New Constraint on Reionization by a Census of $z=7.0$ Ly$\alpha$ Emitters with a Deep and Large Sample to 0.3 $L^*$: Evolution of Ly$\alpha$ Luminosity Function and Equivalent Width at $z\sim6-7$}, url = {http://arxiv.org/abs/1703.02501}, year = 2017 }