Optical spectroscopy of MIR selected AGN candidates

在ISOCAM平行巡天（ISOCAM Parallel Survey）探测到的3000个高星系纬度源中，我们发现了大量极红外的、大多数未知的天体。来自光学波段和2MASS波段的各种颜色标准，以及与已知物体类型的比较，使我们认为我们已经发现了AGN，其核尘埃的中红外辐射在T > 100 K。如果这是真的，这项技术将提供一个新的AGN选择标准，不受消光的影响。因此，我们估计AGN的数量必须大幅修改。为了验证我们的假设，我们选择了120个分类未知的AGN候选对象。我们希望对这些物体进行光谱调查，以便i)确定它们作为AGN的性质，ii)确定在MIR选择的样品中1型和2型AGN的比例。

Among 3000 high galactic latitude sources detected by the ISOCAM Parallel Survey at 6.7 µm we have discovered a population of extremely infrared, mostly unknown objects. Various colour criteria from optical and 2MASS wavebands and the comparison with known object types leads us to suggest that we have found AGN with a pronounced mid-IR emission of nuclear dust at T > 100 K. If true, this technique will provide a new AGN selection criterion, not affected by extinction. As a consequence, we estimate that the number counts of AGN have to be revised dramatically. In order to verify our hypothesis, we have selected 120 of our AGN candidates with yet unknown classification. We wish to perform a spectroscopic survey of these objects in order to i) establish their nature as AGN and ii) to determine the fraction of type 1 and 2 AGN among this MIR selected sample.