2005MNRAS.359..895V

We have used Visible MultiObject Spectrograph Integral-Field Unit observations centred on a radio galaxy at z= 2.9 to search for Lyα emitters within a comoving volume of ∼10⁴Mpc³. We find 14 Lyα emitters with flux >1.4x10^–20/Wm2, yielding a comoving space density of 0.0018^+0.0006_–0.0005/Mpc3. We fit a Schechter luminosity function that agrees well with previous studies both at similar redshift (z∼ 3.4) and higher redshift (z∼ 5.7). We therefore find no evidence for evolution in the properties of Lyα emitters between 3 < z < 6, although our sample is small. By summing the star-formation rates of the individual Lyα emitters we find a total cosmic star-formation rate density of ρ_SFR= 6.7±0.5x10^–3 M_☉/yr/Mpc3. Integrating over the luminosity function for the combined Lyα surveys at z∼ 3.4 and accounting for the difference in obscuration between the Lyα line and the ultraviolet-continuum yields an estimate of ρ_SFR∼ 2.2x10^–2M_☉yr^–1/Mpc3, in line with previous multi-colour and narrow-band surveys of high-redshift star-forming galaxies.

The detection of high-redshift emission-line galaxies in our volumetric search shows that the unique capabilities of wide-field integral-field spectroscopy are well suited to searching for high-redshift galaxies in a relatively unbiased manner.