We present the ZEN ( z equals nine ) survey : a deep , narrow J -band search for proto-galactic Ly \alpha emission at redshifts z \sim 9 .
In the first phase of the survey , dubbed ZEN1 , we combine an exceptionally deep image of the Hubble Deep Field South , obtained using a narrow band filter centred on the wavelength 1.187 \mu m , with existing deep , broad band images covering optical to near infrared wavelengths .
Candidate z \sim 9 Ly \alpha -emitting galaxies display a significant narrow band excess relative to the J _ { s } –band that are undetected at optical wavelengths .
We detect no sources consistent with this criterion to the 90 % point source flux limit of the NB image , F _ { NB } = 3.28 \times 10 ^ { -18 } ergs s ^ { -1 } cm ^ { -2 } .
The survey selection function indicates that we have sampled a volume of approximately 340 h ^ { -3 } Mpc ^ { 3 } to a Ly \alpha emission luminosity of 10 ^ { 43 } h ^ { -2 } ergs s ^ { -1 } .
When compared to the predicted properties of z \sim 9 galaxies based upon no evolution of observed z \sim 6 Ly \alpha -emitting galaxies , the ‘ volume shortfall ’ of the current survey , i.e .
the volume required to detect this putative population , is a factor of at least 8 to 10 .
We also discuss continuing narrow J -band imaging surveys that will reduce the volume shortfall factor to the point where the no-evolution prediction from z \sim 6 is probed in a meaningful manner .