Cumulative LF for Lyα emitters (purple line) derived from subtraction from the search "ALL" counts (blue line) of Schechter-function fits to COSMOS foreground counts (green line). The magenta line is the foreground-subtracted cumulative LF derived using the nominal Schechter LF slopes of α = −1.30, −1.60, and −1.60 ([O ii] , [O iii] , and Hα ), as described in the text. As in the previous figures, the data are cumulative rather than binned: this accounts for the wild excursions at the bright end of the LF, points where the predicted foreground exceeds the few counts of our comparatively small-volume survey. The point of 50% completeness is marked with a short vertical line and a lighter purple to our survey limit. Also shown are SDF LF function extrapolations for the LAE emitters found in narrow-band searches by Shimasaku et al. (2006). Our derived LF for LAEs rises in accordance with the predicted SDF model for a differential faint-end slope of α = −2.0. The cumulative counts in our survey area increase from n ≈ 16 for log L (erg s ⁻¹) >42.55 to n ≈ 122 at the limit of our survey, log L (erg s ⁻¹) =41.95.