论文标题
附近的矮人Galaxy NGC 4395中是否有次数尺度的喷气基座？
Is there a sub-parsec-scale jet base in the nearby dwarf galaxy NGC 4395?
论文作者
论文摘要
NGC 4395是一个矮星系，距离约为4.3 MPC（比例：〜0.021 PC MAS $^{ - 1} $）。它拥有一个中间质量黑洞（IMBH），质量在〜10 $^4 $和〜10 $^5 $太阳能之间。 NGC 4395的早期无线电观察结果具有很长的基线干涉法（VLBI）网络，高灵敏度阵列（HSA），在2005年为1.4 GHz，表明其核具有超过15 MAS的子MJY流出特征（E）。为了探测该功能E作为连续喷气的可能性，其基础与积聚光盘进行了物理结合，我们在5 GHz上对欧洲VLBI网络（EVN）进行了深入的VLBI观察，并分析了2008年的Karl G. jansky Atay Atay（Vla）（VLA），并分析了HSA在1.4 GHz中获得的档案数据，并分析了HSA的档案数据。 237 GHz的毫米/亚毫米阵列（ALMA）。该功能E在2008年的HSA图像中显示了更多的扩散结构，并且在EVN图像中未检测到紧凑的子结构。与精确的光学盖亚位置相同的光学陡峭频谱和极大的角偏移（约220个MAS），我们将特征E解释为IMBH的情节弹出或广角流出可能形成的核冲击。 VLA和ALMA观察发现了一个子MJY PC规模的分散特征，可能会追踪IMBH附近的无热自由发射区域。在VLBI地图中，在IMBH位置无法检测到喷气底座。非检测给出了极低的发光度<= 4.7 x 10 $^{33} $ erg s $^{ - 1} $在5 GHz处，并且没有证据表明子PC量表上的盘式喷射耦合。
NGC 4395 is a dwarf galaxy at a distance of about 4.3 Mpc (scale: ~0.021 pc mas$^{-1}$). It hosts an intermediate-mass black hole (IMBH) with a mass between ~10$^4$ and ~10$^5$ solar masses. The early radio observations of NGC 4395 with the very long baseline interferometry (VLBI) network, High Sensitivity Array (HSA), at 1.4 GHz in 2005 showed that its nucleus has a sub-mJy outflow-like feature (E) extending over 15 mas. To probe the possibility of the feature E as a continuous jet with a base physically coupled with the accretion disc, we performed deep VLBI observations with the European VLBI Network (EVN) at 5 GHz, and analysed the archival data obtained with the HSA at 1.4 GHz in 2008, NSF's Karl G. Jansky Very Large Array (VLA) at 12-18 GHz and the Atacama Large Millimetre/submillimetre Array (ALMA) at 237 GHz. The feature E displays more diffuse structure in the HSA image of 2008 and has no compact substructure detected in the EVN image. Together with the optically thin steep spectrum and the extremely large angular offset (about 220 mas) from the accurate optical Gaia position, we explain the feature E as nuclear shocks likely formed by the IMBH's episodic ejection or wide-angle outflow. The VLA and ALMA observations find a sub-mJy pc-scale diffuse feature, possibly tracing a thermal free-free emission region near the IMBH. There is no detection of a jet base at the IMBH position in the VLBI maps. The non-detections give an extremely low luminosity of <=4.7 x 10$^{33}$ erg s$^{-1}$ at 5 GHz and indicate no evidence of a disc-jet coupling on sub-pc scales.
