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In angle-resolved photoelectron spectra of the antiferromagnetic insulators Ca 2 CuO 2 Cl 2 and Sr 2 CuO 2 Cl 2 , a sharp drop of the spectral intensity of the lowest-lying band is observed along a line in k space equivalent to the Fermi surface of the optimally doped high-temperature superconductors. This was interpreted as a signature of the existence of a remnant Fermi surface in the insulating phase of the high-temperature superconductors. In this paper it is shown that the drop of the spectral intensity is not related to the spectral function but is a consequence of the electron-photon matrix element.

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