On the narrowband detection properties of high-redshift Lyman-alpha emitters

Context. Numerous surveys are currently underway or planned that aim to exploit the strengths of the Lyman-alpha emission line for cosmological purposes. Today, narrowband imaging surveys are frequently used as a probe of the distant universe. Aims. To investigate the reliability of the results of such high-z Lyα studies, and the validity of the conclusions that are based upon them. To determine whether reliable Lyα fluxes (FLyα) and equivalent widths (WLyα) can be estimated from narrowband imaging surveys and whether any observational biases may be present. Methods. We have developed software to simulate the observed line and continuum properties of synthetic Lyα galaxies in the distant universe by adopting various typical observational survey techniques. This was used to investigate how detected FLyα and WLyα vary with properties of the host galaxy or intergalactic medium: internal dust reddening; intervening Lyα absorption systems; the presence of underlying stellar