论文标题
与IRSF/Sirius的Centaurus A的氢重组近红外线映射
Hydrogen recombination near-infrared line mapping of Centaurus A with IRSF/SIRIUS
论文作者
论文摘要
Centaurus A（CEN A）是主持活跃银河核（AGN）的最著名的星系之一，其中研究了AGN活性与周围星际媒介和绘制媒介之间的相互作用。最近的研究报道了从银河光环中的云到CEN A核的东北和西南的Hα发射的检测，这表明AGN喷气机可能触发了恒星的形成。我们使用针对PAβ调整的窄带滤波器对CEN A进行了CEN A的近红外线映射，从中我们发现从东北或西南地区未明显检测到PAβ发射。东北地区PAβ/Hα比的上限与典型的HII区域的预期兼容，这与AGN在那里触发恒星形成的情况一致。另一方面，西南区域的PAβ/Hα上限显着低于典型HII区域的预期。解释西南地区低PAβ/Hα比的可能性是HALO云中的尘土散射Hα和Paβ光子从CEN A的中心散射。从西南地区的PAβ/Hα的上限，我们获得了对灰尘尺寸分布的约束，发现与在星系的星际介质中看到的分布相兼容。
Centaurus A (Cen A) is one of the most famous galaxies hosting an active galactic nucleus (AGN), where the interaction between AGN activities and surrounding interstellar and intergalactic media has been investigated. Recent studies reported detections of the Hα emission from clouds in the galactic halo toward the northeast and southwest of the nucleus of Cen A, suggesting that AGN jets may have triggered star formation there. We performed near-infrared line mapping of Cen A with the IRSF 1.4-m telescope, using the narrow-band filter tuned for Paβ, from which we find that the Paβ emission is not detected significantly from either northeast or southwest regions. The upper limit of the Paβ/Hα ratio in the northeast region is compatible with that expected for a typical HII region, in line with the scenario that AGNs have triggered star formation there. On the other hand, the upper limit of Paβ/Hα in the southwest region is significantly lower than that expected for a typical HII region. A possibility to explain the low Paβ/Hα ratio in the southwest region is the scattering of Hα and Paβ photons from the center of Cen A by dust grains in the halo clouds. From the upper limit of Paβ/Hα in the southwest region, we obtain constraints on the dust size distribution, which is found to be compatible with those seen in the interstellar medium of our Galaxy.
