The Molecular Gas in the NGC 6240 Merging Galaxy System at the Highest Spatial Resolution
The Molecular Gas in the NGC 6240 Merging Galaxy System at the Highest Spatial Resolution
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DOI：
10.3847/1538-4357/ab6b28
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
E. Treister;H. Messias;G. Privon;N. Nagar;A. Medling;V. U;F. Bauer;C. Cicone;Loreto Barcos Muñoz;A. Evans;F. Muller-Sanchez;J. Comerford;L. Armus;Chin-Shin Chang;M. Koss;G. Venturi;K. Schawinski;C. Casey;C. Urry;D. Sanders;N. Scoville;K. Sheth
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文献类型：
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作者：
E. Treister;H. Messias;G. Privon;N. Nagar;A. Medling;V. U;F. Bauer;C. Cicone;Loreto Barcos Muñoz;A. Evans;F. Muller-Sanchez;J. Comerford;L. Armus;Chin-Shin Chang;M. Koss;G. Venturi;K. Schawinski;C. Casey;C. Urry;D. Sanders;N. Scoville;K. Sheth
我们给出了最高分辨率的15 pc（0.″03）-阿尔马12 CO（2-1）谱线发射图和1.3 mm连续谱图，分别是附近合并星系NGC 6240中分子气体和尘埃的示踪物，该星系中有两个同时生长的超大质量黑洞。这些观测提供了一个很好的空间匹配现有的哈勃太空望远镜（HST）的光学和近红外观测这个系统。一个重要的分子气体质量，109 × 109 M，位于两个原子核之间，形成了一个运动学上由湍流主导的团流，而不是之前从低分辨率数据中假设的平滑旋转盘。旋转的证据是在南部核心周围的气体中看到的，而不是在北方核心。可以看到动力壳，可能与核超新星遗迹有关。我们进一步探测到大量高速外流的存在，其中一些达到了>500 km s−1的速度，影响了核区域中相当大一部分分子气体，约占11%。在北方和南方的超大质量黑洞的影响范围内，我们发现分子质量分别为7.4 × 108和3.3 × 109 M Ω。因此，我们直接成像的气体库，可以吸积到每个超大质量黑洞。这些新的阿尔马地图强调了对分子气体进行高分辨率观测的迫切需要，以便了解超大质量黑洞的喂养及其与星系演化的联系。
We present the highest-resolution—15 pc (0.″03)—ALMA 12CO(2–1) line emission and 1.3 mm continuum maps, tracers of the molecular gas and dust, respectively, in the nearby merging galaxy system NGC 6240, which hosts two supermassive black holes growing simultaneously. These observations provide an excellent spatial match to existing Hubble Space Telescope (HST) optical and near-infrared observations of this system. A significant molecular gas mass, ∼9 × 109 M⊙, is located between the two nuclei, forming a clumpy stream kinematically dominated by turbulence, rather than a smooth rotating disk, as previously assumed from lower-resolution data. Evidence for rotation is seen in the gas surrounding the southern nucleus but not in the northern one. Dynamical shells can be seen, likely associated with nuclear supernova remnants. We further detect the presence of significant high-velocity outflows, some of them reaching velocities >500 km s−1, affecting a significant fraction, ∼11%, of the molecular gas in the nuclear region. Inside the spheres of influence of the northern and southern supermassive black holes, we find molecular masses of 7.4 × 108 and 3.3 × 109 M⊙, respectively. We are thus directly imaging the reservoir of gas that can accrete onto each supermassive black hole. These new ALMA maps highlight the critical need for high-resolution observations of molecular gas in order to understand the feeding of supermassive black holes and its connection to galaxy evolution in the context of a major galaxy merger.