Comparison between various predicted SGRB redshift distributions. The grey dashed line represents the convolution of the MD14 cosmic SFH with a delay time distribution P(τ) ∝ τ^-1 with τ> 20 Myr (the normalization is arbitrary). The pink solid line (pink dotted line) represents the redshift distribution of NS−NS binary mergers predicted by Dominik et al. (2013) in their high end (low end) metallicity evolution scenario (standard binary evolution model). The blue dashed line and cyan dot-dashed line are the SGRB redshift distributions according to D14 and to WP15, respectively. The red solid line is our result in case (a), while the orange triple dot-dashed line is our result in case (c). In both cases we used the mean parameter values as listed in Table 1.