Detection of a high brightness temperature radio core in the AGN-driven molecular outflow candidate NGC 1266
Detection of a high brightness temperature radio core in the AGN-driven molecular outflow candidate NGC 1266
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在 AGN 驱动的分子外流候选者 NGC 1266 中检测到高亮温射电核心
DOI：
10.1017/s1743921314000982
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
M. Bureau
中科院分区：
文献类型：
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作者：
K. Nyland;K. Alatalo;J. Wrobel;L. Young;R. Morganti;T. Davis;P. T. de Zeeuw;S. Deustua;M. Bureau
摘要：我们提出了新的 Karl G. Jansky 甚大阵列 (VLA) Hi 吸收和甚长基线阵列 (VLBA) 连续观测活动星系核 (AGN) 驱动的分子外流候选者 NGC 1266。虽然其他众所周知的分子外流系统可能是由中心分子盘中的恒星形成驱动的，但 Alatalo 等人报道的分子质量外流率(2011) 13 M⊙ 年−1 的 NGC 1266 超过了各种示踪剂估计的恒星形成率。这表明额外的能源，例如活动星系核，可能在为外流提供动力方面发挥重要作用。我们的高空间分辨率 Hi 吸收数据揭示了对与假定的 AGN 位于同一位置的射电连续谱核心的紧凑吸收，并且蓝移光谱分量的存在再次证实了气体确实正在流出系统。我们在 1.65 GHz 的 VLBA 观测揭示了分子气体最致密部分内的一个连续谱源，其直径 d < 8 mas (1.2 pc)，无线电功率 Prad = 1.48 × 1020 W Hz−1，亮温 Tb > 1.5 × 107 K，这与 AGN 起源最一致。紧凑型 VLBA 源暗示的射电连续谱能量学，以及较低空间分辨率下的档案 VLA 连续谱观测，进一步支持 NGC 1266 中的 AGN 可能驱动分子外流的可能性。这些发现表明，即使是具有与 Sgr A* 类似的超大质量黑洞的低级活动星系核，也可能能够在其宿主星系中发射大量的外流。
Abstract We present new Karl G. Jansky Very Large Array (VLA) Hi absorption and Very Long Baseline Array (VLBA) continuum observations of the active galactic nucleus (AGN)-driven molecular outflow candidate NGC 1266. Although other well-known systems with molecular outflows may be driven by star formation in a central molecular disk, the molecular mass outflow rate reported in Alatalo et al. (2011) in NGC 1266 of 13 M⊙ year−1 exceeds star formation rate estimates from a variety of tracers. This suggests that an additional energy source, such as an AGN, may play a significant role in powering the outflow. Our high spatial resolution Hi absorption data reveal compact absorption against the radio continuum core co-located with the putative AGN, and the presence of a blueshifted spectral component re-affirms that gas is indeed flowing out of the system. Our VLBA observations at 1.65 GHz reveal one continuum source within the densest portion of the molecular gas, with a diameter d < 8 mas (1.2 pc), a radio power Prad = 1.48 × 1020 W Hz−1, and a brightness temperature Tb > 1.5 × 107 K that is most consistent with an AGN origin. The radio continuum energetics implied by the compact VLBA source, as well as archival VLA continuum observations at lower spatial resolution, further support the possibility that the AGN in NGC 1266 could be driving the molecular outflow. These findings suggest that even low-level AGNs, with supermassive black hole masses similar to Sgr A*, may be able to launch massive outflows in their host galaxies.