The predicted quasar luminosity function calculated by integrating the time spent by a quasar in each luminosity (which I have shown) depends on redshift. When we want to calculate the age of the radio source (activity period) we need to know the redshift and we need to assume some Hubble constant. First we always calculate changes in the angular separation between some radio components (hot spots), but when we want to know the velocity of these changes and the age of the source we have to assume some cosmological parameters.
Magda
On Mon, 17 Feb 2003, Bartosz Lew wrote:
I was inspired by Magda's seminar this monday about the variability of css, gps or whatever. She said that variability is something like a hundret years. And then I thought: shouldn't it (the period) be corrected for the expansion of the universe since these objects happend to be so strongly redshifted ? Or maeybe this effect is negligible.
bartek