标题： 类星体巡天完备性的重新评估：亮星函数的启示 显示英文标题

标题： A new assessment of the completeness of quasar surveys: implications for the luminosity function

摘要： 我们采用一种简单的统计方法（Derenzo & Hildebrand 1969）来估算类星体巡天的完整性。该方法要求某一区域已被两种或更多种，最好是不同的选择技术覆盖。我们使用了三个合适的数据集，分别通过以下方式独立选择：变异性与紫外过量（170个类星体）；客观光谱仪与紫外过量（141个类星体）；多色与X射线（{\it ROSAT,}19个类星体）。我们发现，对于通过紫外过量的选择方式，常见的限制$U-B \le -0.35 \pm -0.05$导致损失$\sim 35%$，通常会遗漏低光度的$(M_{B} \gtrsim -24.5)$类星体，且与红移无关。因此，系统性不完整性将影响新一代基于$U-B \le -0.35$的大型类星体巡天。通过校正这种不完整性，我们从第一个数据集（$B < 21.0$和$z < 2.2$）中得出，类星体亮度函数（LF）的演化最好用亮度和密度联合演化来描述。 当外推至$z = 0$时，LF 比以往的任何确定值都更接近局部 Seyfert 星系的 LF。 与 Boyle 等人 (1990) 的 LF 相比，LF 显示出低红移处低光度类星体数量增加，以及中间红移处明亮类星体数量增加。 这一结果与类星体从初始亮相位逐渐变暗的模型一致。 显示英文摘要

摘要： 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.