DE-SITTER MODEL AND LUMINOSITY - DISTANCE IN COSMOLOGY

The behaviour of luminosity-distance with redshift is analysed within the framework of homogeneous zero-pressure relativistic cosmology. de Sitter's model is shown to have the most redshift sensitive luminosity-distance function of all cosmologies which have qo ≥ -1. Quasar data which suggest a cut-off in absolute luminosity are reanalysed and the cut-off disappears if either de Sitter's model or the assumption L(Lα) = 3 L (Hβ) is used. © 1981 Royal Astronomical Society.