标题： 微弱吉赫兹尖峰谱源的光学光谱学 显示英文标题

标题： Optical spectroscopy of faint gigahertz peaked spectrum sources

摘要： 我们提供了对来自韦斯特博克北天调查（WENSS）的弱Gigahertz峰值谱（GPS）射电源样本的光谱观测。 已经确定了19个（40%）目标的红移。 与低红移星系对应的GPS源的光学光谱显示出深的恒星吸收特征。 这证实了之前的建议，即它们的光学光是未被AGN相关发射显著污染的，而是由年龄大于9 Gyr且金属丰度大于0.2 [Fe/H]的恒星主导，这使得这些（可能）年轻的射电源作为星系演化的探针得到了合理应用。 与类星体对应的GPS源的光学光谱与平坦谱类星体的光谱无法区分，并明显不同于紧凑陡谱（CSS）类星体的光谱。 我们在射电暗样本中GPS类星体的红移分布与文献中亮样本的分布相当，峰值在z ~ 2-3之间。 由于样本中的选择效应，不太可能遗漏大量低红移GPS类星体。 因此，我们认为GPS星系和类星体的红移分布确实存在真实差异，由于这种差异同时存在于射电暗和亮样本中，因此不能归因于红移-光度退化。 因此，除非类星体张角是红移的强函数，否则GPS类星体和星系不太可能是由方向统一的。 我们建议GPS类星体和星系是无关的群体，只是恰好具有相同的观测射电谱特性，并假设GPS类星体是平坦谱类星体的一个子类。 显示英文摘要

摘要： We present spectroscopic observations of a sample of faint Gigahertz Peaked Spectrum (GPS) radio sources drawn from the Westerbork Northern Sky Survey (WENSS). Redshifts have been determined for 19 (40%) of the objects. The optical spectra of the GPS sources identified with low redshift galaxies show deep stellar absorption features. This confirms previous suggestions that their optical light is not significantly contaminated by AGN-related emission, but is dominated by a population of old (>9 Gyr) and metal-rich (>0.2 [Fe/H]) stars, justifying the use of these (probably) young radio sources as probes of galaxy evolution. The optical spectra of GPS sources identified with quasars are indistinguishable from those of flat spectrum quasars, and clearly different from the spectra of Compact Steep Spectrum (CSS) quasars. The redshift distribution of the GPS quasars in our radio-faint sample is comparable to that of the bright samples presented in the literature, peaking at z ~ 2-3. It is unlikely that a significant population of low redshift GPS quasars is missed due to selection effects in our sample. We therefore claim that there is a genuine difference between the redshift distributions of GPS galaxies and quasars, which, because it is present in both the radio-faint and bright samples, can not be due to a redshift-luminosity degeneracy. It is therefore unlikely that the GPS quasars and galaxies are unified by orientation, unless the quasar opening angle is a strong function of redshift. We suggest that the GPS quasars and galaxies are unrelated populations and just happen to have identical observed radio-spectral properties, and hypothesise that GPS quasars are a sub-class of flat spectrum quasars.