Dense arrays of core–shell nanowires possess great potential as superabsorptive media for the fabrication of efficient solar cells. We report on GaAs near-band-edge absorption properties of free-standing GaAs–AlGaAs core–shell nanowires having different shell thicknesses, by detailed line-shape analyses of room-temperature photoreflectance (PR) spectra, employing first-derivative Gaussian and Lorentzian models of the GaAs complex dielectric function. Line-shape analyses of the nanowire PR spectra returned a doublet of resonance lines at energies between 1.410 and 1.422 eV, ascribed to strain-split heavy- and light-hole exciton absorption transitions in the GaAs nanowire cores. The optical oscillator strengths of exciton resonances evaluated by Lorentzian analyses of PR features showed a significant enhancement (up to 30×) of GaAs band-edge optical absorption in nanowires with respect to the …