A Subaru Search for Lyman$\alpha$ Emitters at Redshift 5.7

Abstract

We present the results of a survey for Ly$\alpha$ emitters at $z\approx 5.7$ based on optical narrow-band (${\lambda }_{\mathrm{c}}=8150$ Å~ and $\Delta \lambda =120$ Å), and broad-band ($B$, $R_{\mathrm{C}}$, $I_{\mathrm{C}}$, and $z^{\prime }$) observations of the field surrounding the high redshift quasar, SDSSp J104433.04$-$012522.2, on the 8.2 m Subaru Telescope with the Subaru Prime Focus Camera, Suprime-Cam. This survey covers a sky area of $\approx 720$ arcmin${}^2$ and a co-moving volume of $\simeq 2\times 10^5{h}_{0.7}^{-3}$ Mpc${}^3$. We have found 20 candidates of Ly$\alpha$ emitters at $z\approx$ 5.7 with $\Delta z\approx 0.1$. Two of them have been confirmed star-forming galaxies at $z=5.655$ and $z=5.687$ from our follow-up optical spectroscopy. We discuss star-formation properties of the 20 objects from a statistical point of view. Our survey leads to a new estimate of the star formation rate density at $z\approx 5.7$, $\sim 1.2\times 10^{-3}{h}_{0.7}{M}_{\odot }$ yr${}^{-1}$ Mpc${}^{-3}$.

18 pages, 19 figures, accepted for AJ