Astronomy and Astrophysics – Astrophysics
Scientific paper
1998-10-02
Astronomy and Astrophysics
Astrophysics
22 pages, 2 figures, to appear in ApJ
Scientific paper
10.1086/306836
We apply a simple statistical method (Derenzo & Hildebrand 1969) to estimating the completeness of quasar surveys. It requires that an area has been covered by two or more, preferably different, selection techniques. We use three suitable data sets with separate selections from: variability and UV-excess (170 quasars); objective prism and UV-excess (141 quasars); multicolour and X-ray ({\it ROSAT,} 19 quasars). We find that, for selection by UV-excess, the common limit of $U-B \le -0.35 \pm -0.05$ leads to losses of $\sim 35%$, typically missing low-luminosity $(M_{B} \gtrsim -24.5)$ quasars, independently of redshift. Systematic incompleteness will therefore affect the new generation of large quasar surveys that select by $U-B \le -0.35$. By correcting for this incompleteness, we find, from the first data set ($B < 21.0$ and $z < 2.2$), that the evolution of the quasar luminosity function (LF) is best described by joint luminosity and density evolution. When extrapolated to $z = 0$, the LF matches that of local Seyfert galaxies better than any previous determination. The LF shows an increase in the number of low-luminosity quasars at low redshifts and of brighter quasars at intermediate redshifts, relative to the LF of Boyle et al. (1990). This result is consistent with models in which quasars fade from an initial bright phase.
Campusano Luis E.
Clowes Roger G.
Graham Matthew J.
No associations
LandOfFree
A new assessment of the completeness of quasar surveys: implications for the luminosity function does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A new assessment of the completeness of quasar surveys: implications for the luminosity function, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A new assessment of the completeness of quasar surveys: implications for the luminosity function will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-341526