Hα luminosity density of the Universe as a function of redshift. The solid thick lines show the total luminosity density, whereas the thin solid curves show the luminosity density for emitters at F> 10^-16 erg cm^-2 s^-1 (upper set of curves) and F> 3 × 10^-16 erg cm^-2 s^-1 (lower set of curves). The different colours are codes for each model (blue, Model 1; black, Model 2; and red, Model 3). Also shown is the calculation of total Hα luminosity density based on the star formation histories of Madau & Dickinson (2014, green dashed) and Behroozi et al. (2013, gray dashed and shaded area). On the right axis we report also the SFR density scale for a Chabrier IMF.