天文光度函数(英文)

Astronomical Luminosity Functions

至少从托勒玫时代以来，天体的计数已成为天文学的一部分。光度函数是作为某一波段的光度或亮度的函数的特定种类的天体数目。而视亮度的相应概念通常叫作计数。虽然有点夸张，但这些工具仍是检验天体物理假设和检验天体物理新概念的强有力的手段。本评论来源于1995年1月份为MaartenSchmidt诞生65周年而召集的一次学术会议。可用以研究光度函数的重要天体包括很暗的恒星、γ射线暴、亮类星体和其他活动星系，及不可见辐射源。特别令人惊奇的是：很暗的恒星少，而很暗的星系数目非常大。一个重要而尚未解决的问题是：我们是否足够好地了解，甚至是否能够足够好地了解星系、星系团、射电和X射线源的内禀天体物理性质及其演化，以便用这些天体作为宇宙学和宇宙大尺度结构参数的探针。

Counting objects has been part of astronomy at least since the time of Ptolemy.A luminosity function is the number of objects of a particular sort as a function of their luminosity or brightness in some wavelength band. The corresponding concept for apparent brightness is generally called a number count. Though simple-sounding, thesetools are remarkably powerful ones for testing astrophysical hypotheses and suggesting new ones. This review has its origins in a conference held in January, 1995, honoring the 65th birthday of Maarten Schmidt. The important kinds of objects whose luminosityfunctious are useful to study include the very faintest stars, gamma ray bursters, brightquasars and other artive galaxies, and sources of non-visible radiation. Particularly surprising are the rarity of the faintest stars and the extraordinarily large numbers of very faint galaxies. An important unsettled question is whether we understand, or ever can understand, the intrinsic, astrophysical properties of galaxies, clusters, radio and X-ray sources, and their evolution well enough to use them as probes of cosmology and the large scale structure parameters of the universe.