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tokens: the measured Ly profiles in Fig. 4 feature a more or less pronounced inwards upturn around a radius of 1, suggesting either a superposition of a compact emission component on top of a more extended one, or alternatively a more complicated radial law. Modelling such curved profiles as single exponentials would yield spurious values for the scale lengths that strongly depended on the chosen radial range for the fitting. We adopted a two-component model as the functional form fitted to the Ly SB distributions of each object, decomposing it into two distinct components. The first was taken to resemble that of the compact UV continuum; we call it the “continuum-like” component and assume that its shape parameters are precisely known from our GALFIT modelling of the HST images (i.e. as elongated exponential discs or as point sources), except for a single flux scaling factor related to the Ly EW of this component. The Ly halo, on the other hand, was again parametrised as a single exponential. Since in this paper we only aim at obtaining robust estimates of the azimuthally averaged halo sizes, we enforced the halo model to be circularly symmetric; we also assumed both components to be concentric (see Sect. 4.4 for a brief discussion of the fitting results when these restrictions were relaxed). There were thus 3 free parameters to be optimised in each fit: The integrated fluxes and of both Ly components, and the exponential scale length of the halo. We present the results from these fits in the next subsection. Our two-component model can be seen as a minimalistic extension of the conventional single exponential profile, but it may also represent a physically meaningful hypothesis: If some fraction of the Ly luminosity produced within the star-forming regions escapes (more or less) directly – possibly suffering from dust attentuation but without large-scale spatial redistribution – then this Ly emission will roughly follow our continuum-like component. The halo component, on the other hand, describes the Ly emission more extended than the continuum, irrespective of whether it has its origin inside the galaxy and then got scattered outwards, or whether it is produced by mechanisms other than recombination in H ii regions. An alternative approach to model the Ly SB distribution would be to replace the separation into two components by a more flexible single SB law for the Ly profile such as a Sersic function. Note that a circular Sersic profile has again 3 free parameters to be fitted (total flux, half-ligh radius and Sersic index). We explored such fits as well and briefly report about the outcome below. Fig. 7 Decomposition of the observed Ly surface brightness distributions into a compact (continuum-like) and an extended exponential component (halo), as described in the text. Only the objects with detected haloes () are shown. The datapoints are the same as in Fig. 4 , but now plotted against linear radii. The green curves show the profiles of the