Universe luminosity density

The pioneering investigation in this field was that by Partridge and Peebles (1967 hereinafter PP), who computed a number of evolutionary synthesis models for a typical galaxy, assumed similar to our own. These were based on the present-day luminosity density of the Universe (see Eq. 4.57) and the relation... 

The best fit rather indicates the presence of dark energy. This conclusion was largely determined by the object with largest z observed to date. In 2001, a SN la with z = 1.6 was reported with larger apparent luminosity than expected in a matter dominated or in an empty Universe (Riess et al. 2001, see Fig. 12.3). It can be reconciled with the small z observations by assuming that it exploded in an epoch when the matter part of the energy density was still dominant and the rate of the expansion was decreasing. Quantitatively, the fit led to = 0.35, Qa = 0.65. 

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