2014MNRAS.443.2384Z

Using simulations, we demonstrate that some of the published redshift distributions of submillimetre galaxies at different wavelengths, which were previously reported to be statistically different, are consistent with a parent distribution of the same population of galaxies. The redshift distributions which peak at zmed = 2.9, 2.6, 2.2, 2.2, and 2.0 for galaxies selected at 2 and 1.1 mm, and 870, 850, and 450 µm, respectively, can be derived from a single parent redshift distribution, in contrast with previous studies. The differences can be explained through wavelength selection, depth of the surveys and, to a lesser degree, angular resolution. The main differences are attributed to the temperature of the spectral energy distributions, as shorter wavelength maps select a hotter population of galaxies. Using the same parent distribution and taking into account lensing bias, we can also reproduce the redshift distribution of 1.4-mm-selected ultra-bright galaxies, which peaks at zmed = 3.4. However, the redshift distribution of 450-µm-selected galaxies in the deepest surveys, which peaks at zmed = 1.4, cannot be reproduced from the same parent population with just these selection effects. In order to explain this distribution, we have to add another population of galaxies or include different selection biases.