Search for z~6.96 Ly-alpha emitters with Magellan/IMACS in the COSMOS field

TL;DR

This study searches for Ly-alpha emitters at redshift 6.96 using narrow-band imaging, deriving a luminosity function and comparing it with lower-redshift data, pending spectroscopic confirmation.

Contribution

First narrow-band survey at z~6.96 providing a Ly-alpha luminosity function and comparison with previous redshift data.

Findings

Sample of 6 LAE candidates identified.

No evolution observed in Ly-alpha LF from z=5.7 to z~7.

Spectroscopic follow-up needed for confirmation.

Abstract

We report a search for z~6.96 Ly-alpha emitters (LAEs) using a Narrow-Band filter, centered at 9680 Angstroms, with the IMACS instrument on the Magellan telescope at Las Campanas Observatory. We obtain a sample of 6 Ly-alpha emitter candidates of luminosity ~10^42 erg/s in a total area of 465 square arcmin corresponding to a comoving volume of ~ 72000 Mpc^3. From this result, we derive a Ly-alpha luminosity function (LF) at z~6.96 and compare our sample with the only z~6.96 Ly-alpha emitter spectroscopically confirmed to date (Iye et al. 2006). We find no evolution between the z=5.7 and z~7 Ly-alpha luminosity functions, if a majority of our candidates are confirmed. Spectroscopic confirmation for this sample will enable more robust conclusions.