Spatial profile of the Lyα emission (top) and quasar continuum (bottom) along the slit. The Lyα profile has been averaged over 10 pixels centred at the Lyα position (4211.8 Å). The quasar continuum profile has been averaged over the wavelength range free of strong absorption (4135−4150 Å). In each panel, we show the best-fit Gaussian model to the data. The vertical dashed lines indicate the centres of the profiles.