3.3半人马座A中心千秒差距的μm PAH观测
3.3 μm PAH observations of the central kiloparsecs of Centaurus A
摘要：
目标。这项工作的目的是进一步调查PAH的激发和发射的性质，特别是在跟踪恒星形成的背景下，在各种河外环境。在这里，我们将注意力转向我们样本中最近的活动星系核，半人马座A的能量环境。方法.利用ESO VLT UT1（Antu）上的ISAAC对CenA中心千秒差距进行了高空间分辨率3.3 μm成像观测。这些观测结果与近红外和中红外的恒星形成示踪物以及核活动的中红外示踪物进行了比较。结果原子核并非没有多环芳烃发射，这意味着多环芳烃颗粒并未在原子核中被破坏，正如在如此恶劣的环境中所预期的那样。然而，我们看到的功能，连续比减少向活动星系核。此外，3.3 μm的PAH特征辐射通常可以追踪到Cen A的恒星形成地点，但在细节上存在空间偏移，这与早期对星暴星系NGC 253和NGC 1808的研究一致。然而，在恒星形成的位置，特征与连续统的比率并没有像以前在早期研究中看到的那样下降。造成这种差异的原因仍然不确定。最后，我们的数据揭示了可能的证据，即围绕核的尘埃结构几乎是正面的，圆形或螺旋形。
英文摘要：
Aims. The aim of this work is to further investigate the nature of PAH excitation and emission especially in the context of tracing star formation in a variety of extragalactic environments. Here we turn our attention to the energetic environment of the closest AGN in our sample, Centaurus A. Methods. Using ISAAC on the ESO VLT UT1 (Antu) we have made high spatial resolution 3.3 μm imaging observations of the central kiloparsec of CenA. These observations have been compared with star formation tracers in the near- and mid-infrared, as well as with mid-infrared tracers of nuclear activity. Results. The nucleus is not devoid of PAH emission, implying that the PAH particles are not destroyed in the nucleus as might be expected for such a harsh environment. However, we see the feature to continuum ratio decrease towards the AGN. As well, the 3.3 μm PAH feature emission generally traces the sites of star formation in Cen A, but in detail there are spatial offsets, consistent with an earlier study of the starburst galaxies NGC 253 and NGC 1808. However, the feature-to-continuum ratio does not drop at the positions of star formation as was previously seen in that earlier study. The cause for this difference remains uncertain. Finally, our data reveal possible evidence for a nearly face-on, circular or spiral, dust structure surrounding the nucleus.
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