the strong evolution of the quasar luminosity function between redshifts 0 and 2 is the most dramatic example of evolution in extragalactic astronomy. nevertheless theoretical accounts of the causes of this evolution remain speculative. this is because there is little observational data, besides the luminosity function itself, with which to constrain the theories. the ir properties of quasars can furnish valuable clues to the causes of evolution. for example (i) if high-redshift quasars z>2 reside in forming galaxies we may expect to observe an increase in star-forming activity at these redshifts, and (ii) if the evolution is partly led by evolving torus opening angles, this should be reflected in the mid- and far-ir radiation. the gto quasar samples are not well suited to an investigation of the redshift and luminosity dependence of the ir properties of quasars. this is because the restricted range in apparent magnitude means that luminosity and redshift are strongly coupled in these samples. instead we have selected samples that span a wide range in both absolute magnitude and redshift. this will allow us to investigate correlations with luminosity and redshift independently. our sample of radio-quiet quasars complement other proposals of ours aimed at investigating the properties of radio galaxies and radio-loud quasars. combining the different samples will provide constraints on models of agn unification, perhaps yeilding clues towards understanding the difference between radio-quiet and radio-loud objects.
Instrument
PHT22
Temporal Coverage
1997-01-04T12:02:08Z/1998-01-16T03:43:34Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
