curve, the likelihood of the data as a function of $\alpha$, normalised to the peak. This is the posterior pdf (modulo a constant) for $\alpha$ adopting a uniform prior. The best fit, plotted as the stretched curve in Figure \[fig:lbg\_cumf\] is $\alpha(obs)=1.9\pm0.2$. The probability of the data if $\alpha$ is as large or larger than $\alpha(req)=2.64$ is $p=0.013$. This means that the measured rotation velocities are too small to be consistent with the massive–halo model. Another way of visualising this result is to say that the rotation velocities imply a distribution of $V_{c7}$ for LBGs which is the distribution of $\sigma$ plotted in Figure \[fig:lbg\_mmwdistribution\] stretched by the factor $\alpha(obs)=1.9$. The circular velocities are smaller than the predicted circular velocities for the massive–halo model by a factor $1.4\pm0.15$.

![\[fig:lbg\_bayesians\]Likelihood plots (normalised to the peak) to show the effects of changing parameters in the model. The upper plot shows the effect of changing the atmospheric seeing, and the lower plot shows the effect of varying the concentration. All other parameters are kept fixed at the preferred values.](./images/PLOT_seeing "fig:"){width="0.85\columnwidth"} ![\[fig:lbg\_bayesians\]Likelihood plots (normalised to the peak) to show the effects of changing parameters in the model. The upper plot shows the effect of 