标题： 塞弗特2型星系NGC 2110中硅酸盐发射特征的起源 显示英文标题

标题： The Origin of the Silicate Emission Features in the Seyfert 2 Galaxy, NGC 2110

摘要： 活动星系核（AGN）的统一模型预测了I型AGN中10和18微米处的硅酸盐发射特征，而这些特征现在已经出现在从遥远的QSO到附近的LINERs的各种天体中。 然而，更令人惊讶的是在少数II型AGN中检测到硅酸盐发射。 通过结合NGC 2110（已知最近的具有硅酸盐发射特征的塞弗特II型星系）的Gemini和斯皮策中红外成像与光谱数据，我们可以将硅酸盐发射区域的位置限制在距离星系核32秒差距以内。 这是迄今为止对任何类型的塞弗特星系中硅酸盐发射区域大小的最强约束。 尽管这一结果与窄线区发射起源一致，但与块状星系盘模型的比较表明，边缘视图的星系盘发射也可以解释该天体的硅酸盐发射特征和2-20微米的光谱能量分布。 在许多最佳拟合模型中，星系盘沿视线方向仅有少量云团，并且不会延伸至赤道平面以上很远。 虽然在AGN中可能存在扩展的硅酸盐发射区域，但这项工作确立了星系盘本身的发射也是I型和II型活跃星系核中硅酸盐发射特征的一个可行来源。 显示英文摘要

摘要： The unified model of active galactic nuclei (AGN) predicts silicate emission features at 10 and 18 microns in type 1 AGN, and such features have now been observed in objects ranging from distant QSOs to nearby LINERs. More surprising, however, is the detection of silicate emission in a few type 2 AGN. By combining Gemini and Spitzer mid-infrared imaging and spectroscopy of NGC 2110, the closest known Seyfert 2 galaxy with silicate emission features, we can constrain the location of the silicate emitting region to within 32 pc of the nucleus. This is the strongest constraint yet on the size of the silicate emitting region in a Seyfert galaxy of any type. While this result is consistent with a narrow line region origin for the emission, comparison with clumpy torus models demonstrates that emission from an edge-on torus can also explain the silicate emission features and 2-20 micron spectral energy distribution of this object. In many of the best-fitting models the torus has only a small number of clouds along the line of sight, and does not extend far above the equatorial plane. Extended silicate-emitting regions may well be present in AGN, but this work establishes that emission from the torus itself is also a viable option for the origin of silicate emission features in active galaxies of both type 1 and type 2.