A flux-limited sample of z ∼ 1 Lyα emitting galaxies in the Chandra Deep Field South.
BARGER A.J., COWIE L.L. and WOLD I.G.B.
Abstract (from CDS):
We describe a method for obtaining a flux-limited sample of Lyα emitters from Galaxy Evolution Explorer (GALEX) grism data. We show that the multiple GALEX grism images can be converted into a three-dimensional (two spatial axes and one wavelength axis) data cube. The wavelength slices may then be treated as narrowband images and searched for emission-line galaxies. For the GALEX NUV grism data, the method provides a Lyα flux-limited sample over the redshift range z = 0.67-1.16. We test the method on the Chandra Deep Field South field, where we find 28 Lyα emitters with faint continuum magnitudes (NUV > 22) that are not present in the GALEX pipeline sample. We measure the completeness by adding artificial emitters and measuring the fraction recovered. We find that we have an 80% completeness above a Lyα flux of 10–15 erg/cm2/s. We use the UV spectra and the available X-ray data and optical spectra to estimate the fraction of active galactic nuclei in the selection. We report the first detection of a giant Lyα blob at z < 1, though we find that these objects are much less common at z = 1 than at z = 3. Finally, we compute limits on the z ∼ 1 Lyα luminosity function and confirm that there is a dramatic evolution in the luminosity function over the redshift range z = 0-1.
cosmology: observations - galaxies: active - galaxies: distances and redshifts - galaxies: evolution - galaxies: starburst