Hydrogen recombination near-infrared line mapping of Centaurus?A with IRSF/SIRIUS
Hydrogen recombination near-infrared line mapping of Centaurus?A with IRSF/SIRIUS
复制标题
使用 IRSF/SIRIUS 绘制 Centaurus?A 氢复合近红外线图
DOI：
10.1093/pasj/psaa081
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发表时间：
2020
影响因子：
2.3
通讯作者：
Tsuchikawa Takuro
中科院分区：
文献类型：
--
作者：
Katayama Risako;Kaneda Hidehiro;Kokusho Takuma;Morihana Kumiko;Suzuki Toyoaki;Oyabu Shinki;Yamagishi Mitsuyoshi;Tsuchikawa Takuro
半人马座A(Cen A)是最著名的拥有活动星系核(AGN)的星系之一，研究了AGN活动与周围星际和星际介质之间的相互作用。最近的研究报告说，探测到星系晕中的云向Cen-A核的东北和西南方向发射Hα，这表明活动星系核喷流可能在那里触发了恒星的形成。我们用IRSF1.4 m望远镜对Cen-A进行了近红外线的测绘，并使用了针对Paβ调谐的窄带滤光片，从中我们发现无论是东北还是西南地区都没有明显地探测到Paβ发射。东北地区的Paβ/Hα比值的上限与一个典型的高海拔地区的预期上限是一致的，符合活动星系核在那里触发恒星形成的情景。另一方面，西南地区的Paβ/Hα的上限明显低于典型高海拔地区的预期。西南部地区较低的Paβ/Hα比值的一个可能解释是晕云中的尘埃粒子从Cen-A中心散射Hα和Paβ光子。根据西南区的Paβ/Hα的上限，我们得到了尘埃大小分布的约束，这与我们在银河系星际介质中所看到的是一致的。
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 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 Paβ emission is not detected significantly from either of the northeast or southwest regions. The upper limit of the Paβ/Hα ratio in the northeast region is compatible with that expected for a typical Hiiregion, 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 Hiiregion. A possible explanation of 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.