标题： 亚毫米波选中的类星体位于阿贝尔478星field之中 显示英文标题

标题： A Submillimetre Selected Quasar in the Field of Abell478

摘要： 我们报告了对一个尘埃丰富的类星体 SMMJ04135+10277 的发现，该类星体位于阿贝尔 478 星系团之后。 这个类星体是在一项旨在研究尘埃星系宇宙恒星形成历史的项目中，作为前景丰富星系团透镜高红移星系亚毫米波段巡天中最亮的源被发现的。 凭借其亚毫米波段通量 S_850 = 25±2.8 mJy 和 S_450 = 55±17 mJy，这一目标物是已知最亮的亚毫米波源之一。 光学观测揭示了一个红移 z=2.837 的类星体。 此外，使用红外空间望远镜，在较短的红外波长下也检测到了该类星体。 此目标物是首个通过其亚毫米波发射被发现的类星体。 鉴于深亚毫米波样本和 X 射线样本之间的普遍重叠缺乏，通常解释为亚毫米波样本中活跃核的比例较低，这是一个不同寻常的目标。 类星体和亚毫米波星系的数量计数分析证实了这一点。 我们将 SMMJ04135+10277 的特性与那些通过光学选择且具有亚毫米波发射的类星体进行了比较，并认为其光学上的暗弱是由于相对论性束流方向的大视角，而非异常高的消光。 我们还发现大部分亚毫米波通量密度并非由类星体核提供能量。 红外光谱能量分布的分析支持了这一结论。 这些结果与先前的观测一致，即更高红移的类星体倾向于有更显著的冷尘埃成分，这很可能由宿主星系中的扩展恒星形成所驱动。 该类星体的总红外光度为 (2.9±0.5)×10^13 L_sun，主要由冷尘埃的辐射主导。 （摘要） 显示英文摘要

摘要： We present the discovery of a dusty quasar, SMMJ04135+10277, located behind the galaxy cluster Abell 478. The quasar was discovered as the brightest source in a submillimetre survey of high redshift galaxies lensed by foreground rich clusters of galaxies in a project aimed at studying the cosmic star formation history of dusty galaxies. With submm fluxes of S_850 = 25+-2.8 mJy and S_450 = 55+-17 mJy this object is one of the brightest submillimetre sources known. Optical observations revealed a quasar with redshift z=2.837. The quasar was also detected at shorter infrared wavelengths with the Infrared Space Observatory. This object is the first quasar discovered by its submm emission. Given the general lack of overlap between deep submm and X-ray samples, usually interpreted as a low incidence of active nuclei in submm samples, this is an unusual object. Analysis of number counts of quasars and of submm galaxies bears out this suggestion. We compare the properties of SMMJ04135+10277 to those of optically selected quasars with submm emission, and argue that the optical faintness results from a large viewing angle with the direction of relativistic beaming, and not from abnormally high extinction. We also find indications that the bulk of the submm flux density is not powered by the quasar nucleus. This conclusion is supported by analysis of the infrared spectral energy distribution. These results are consistent with previous observations that quasars at higher redshift tend to have a more prominent cold dust component, most likely powered by extended star formation in the host galaxy. The quasar is found to have a total infrared luminosity of (2.9+-0.5)x10^13 L_sun, dominated by the emission from cool dust. (Abridged)