Luminosity evolution and the diffuse background

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 IRAS satellite mission, launched in 1983, provided a more complete survey of disk and active galaxies containing dust than had been possible from optical observations. Follow-up measurements of redshifts and other properties led to significant results for cosmology and the discovery of many luminous star-forming and active galaxies enshrouded by dust. A typical spiral galaxy like our own 

2 Although Peebles had himself recently completed a calculation of primordial element synthesis including helium (Peebles 1966). 

Cosmic chemical evolution and diffuse background radiation 

The IRAS galaxies provided some of the earliest evidence from redshift surveys, and from source counts as a function of observed flux, that the spiral galaxy population has undergone evolution (ORS see Fig. 12.2). This result is analogous to similar evidence from source counts of radio galaxies and quasars, as well as quasar redshifts, and a correlation that has been observed between radio and infrared luminosity suggests that the evolution could be similar in both cases. Typical simple models for such evolution include luminosity evolution according to 

---