The luminosity function of Lyα emitters at 2.3 < z < 4.6 from integral-field spectroscopy

Abstract

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 ∼104 Mpc3. We find 14 Lyα emitters with flux >1.4 × 10-20 W m -2, yielding a comoving space density of 0.0018 -0.0005+0.0006 Mpc-3. 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 ρSFR = 6.7 ± 0.5 × 10-3 M⊙ yr -1 Mpc-3. 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 ρSFR ∼ 2.2 × 10-2 M⊙ yr-1 Mpc-3, 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. © 2005 RAS.