标题： 类星体活动高峰时宿主星系的性质 显示英文标题

标题： The properties of quasar hosts at the peak of the quasar activity

摘要： 我们展示了使用欧洲南方天文台甚大望远镜/红外照相机（ESO VLT/ISAAC）获得的一组16个低光度射电安静类星体在类星体活动高峰时期（2 < z < 3）的近红外图像，目的是研究它们的宿主星系。对于11个类星体，我们能够探测到宿主星系并推导出其性质，而对于另外5个类星体，则估计了宿主星等的上限。高红移射电安静类星体的宿主星系光度范围与大质量非活动椭圆星系的光度相当。这项工作补充了我们之前对类星体宿主星系的系统研究，旨在追踪宿主星系到z ~2时的宇宙光度演化，并扩展了我们对少数几个z > 2亮类星体的初步研究。宿主星系随宇宙时间的光度趋势与大质量非活动星系所观察到的趋势相似，表明它们有类似的恒星形成历史。特别是，类星体宿主星系和大质量非活动星系在类星体活动高峰期就已经基本形成。这一结果对于测试星系及其活跃核的共同形成和演化的模型具有重要意义。 显示英文摘要

摘要： We present near-infrared imaging obtained with ESO VLT/ISAAC of a sample of 16 low luminosity radio-quiet quasars at the epoch around the peak of the quasar activity (2 < z < 3), aimed at investigating their host galaxies. For 11 quasars, we are able to detect the host galaxies and derive their properties, while for the other five quasars, upper limits to the host luminosity are estimated. The luminosities of the host galaxies of radio-quiet quasars at high redshift are in the range of those of massive inactive elliptical galaxies. This work complements our previous systematic study of quasar hosts aimed to trace the cosmological luminosity evolution of the host galaxies up to z ~2 and extends our pilot study of a few luminous quasars at z > 2. The luminosity trend with cosmic epoch resembles that observed for massive inactive galaxies, suggesting a similar star formation history. In particular, both quasar host galaxies and massive inactive galaxies appear mostly assembled already at the peak age of the quasar activity. This result is of key importance for testing the models of joint formation and evolution of galaxies and their active nuclei.