标题： 10和18微米类星体硅酸盐发射的探测 显示英文标题

标题： The Detection of Silicate Emission from Quasars at 10 and 18 Microns

摘要： 我们报告了在五个PG类星体中10和18微米硅酸盐发射谱线的光谱探测，这是首次在外群星系中检测到这两个特征。 这一发现与活动星系核（AGN）的统一模型一致，该模型预测从正面看到的AGN星团应该在中红外波段显示出硅酸盐发射特征。 检测到的硅酸盐发射特征强度在10微米处为连续谱的0.12至1.25倍，在18微米处为0.20至0.79倍。 假设发射是光学薄的情况下，由18至10微米硅酸盐特征的比例推断出的硅酸盐颗粒温度范围从140到220K。 显示英文摘要

摘要： We report the spectroscopic detection of silicate emission at 10 and 18 microns in five PG quasars, the first detection of these two features in galaxies outside the Local Group. This finding is consistent with the unification model for Active Galactic Nuclei (AGNs), which predicts that an AGN torus seen pole-on should show a silicate emission feature in the mid-infrared. The strengths of the detected silicate emission features range from 0.12 to 1.25 times the continuum at 10 microns and from 0.20 to 0.79 times the continuum at 18 microns. The silicate grain temperatures inferred from the ratio of 18-to-10 micron silicate features under the assumption of optically thin emission range from 140 to 220K.