at optical wavelengths we know that quasars evolve such that at a given luminosity the space density increases as redshift increases up to a redshift of 2-3, but we do not know whether this change is due to density or luminosity evolution. we intend to do photometry on a sample of bright quasars at a variety of wavelengths, at 7.3, 11.5, 25, 60, and 100 microns. with these data we will determine the spectral energy distributions. this sample of quasars has been carefully constructed such that it spans a wide range in redshift and a narrow range in optical luminosity, in order to eliminate the usual luminosity-redshift degeneracy inherent in most quasar samples. with this sample of quasars we will be able to see if the ir s.e.d.s of the quasars also change with redshift and we can test the hypothesis that the observed evolution in the optical is due to the evolution in the covering factor of dust. the quasars have been selected from hewitt and burbidge, and the recently completed edinburgh multicolour quasar survey. none of the sources are in the central program. iso data is essential for this experiment as we need to measure the s.e.d.s of these sources in the ir and over as wide a wave- length range as possible. note- two diagrams are included in the paper version of this proposal but are excluded from the electronic version.
Instrument
PHT03 , PHT22
Temporal Coverage
1996-07-21T01:48:24Z/1998-01-29T12:44:16Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's 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.
