Notes. Main columns are: (1) sample: for the characteristics of the different samples considered see comments in Col. (6) and main text; (2) n: number of objects in each sample; (3) r_1/2(Hα): intrinsic (deconvolved) Hα half-light radius; (4) logarithm of the dereddened Hα luminosity surface density within the half-light radius, r_1/2(Hα). Note that Σ_Hα = L(Hα)/(), where L(Hα) is the total Hα luminosity and the factor 2 takes into account that within the half-light radius only half of the flux is included; (5) star formation rate surface density within r_1/2(Hα), obtained from Σ_Hα following Kennicutt (1998); (6) comments where: (i) sample observed via IFS with INTEGRAL and VIMOS-IFUs. Mrk 273 is not included in the luminosity calculations, as no IFS calibrated data exists (GM09b). For Arp 220, the Hα luminosity was obtained from Colina et al. (2004), while for the rest of the sample they come from GM09b and RZ11 (see text). This sample is divided at log (L_ir/L_⊙) = 11.4 because r_1/2 values for the subsample above this limit are virtually unaffected by FoV, while for a large fraction of objects below this luminosity only lower limits to their size could be obtained (see text, and Fig. 1). (ii) Galaxies C and S of IRAS 06259-4708 are not included as it is uncertain whether they belong to this group as no reliable individual values for their infrared luminosity exits. In any case, the reported statistical values do not change by their inclusion. (iii) Objects with evidence of hosting an AGN have been removed from this sample. (iv) For a large fraction of objects in this luminosity range, the r_1/2 determinations are significantly affected by the small FoV of the IFS instruments used and, therefore, these values should be only considered as lower limits. (v) Local U/LIRGs with (dereddened) L(Hα) > 10⁴² erg s^-1 and observed on similar linear scales as the selected high-z samples. (vi) This set excludes objects classified as interacting and pre-coalescence systems. IRAS F11087+5355, which is at the border of the definition of a pre-coalescence system (see GM09a) is also excluded. (vii) Only interacting and pre-coalescence systems (IRAS F11087+5355 is also included). (viii) high-z SFGs observed in Hα with IFS systems with high angular resolutions. They include the works of: Förster Schreiber et al. (2009), Law et al. (2009), Wright et al. (2009), and Wisnioski et al. (2011). (ix) This sample includes only the IR-selected sources of the SINS sample of Förster Schreiber et al. (2009).