A Precision Measurement of the Mass of the Black Hole in NGC 3258 from High-resolution ALMA Observations of Its Circumnuclear Disk
A Precision Measurement of the Mass of the Black Hole in NGC 3258 from High-resolution ALMA Observations of Its Circumnuclear Disk
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DOI：
10.3847/1538-4357/ab2a0a
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发表时间：
2019-06
期刊：
影响因子：
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通讯作者：
Benjamin D. Boizelle;A. Barth;J. Walsh;D. Buote;A. Baker;J. Darling;L. Ho
中科院分区：
文献类型：
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作者：
Benjamin D. Boizelle;A. Barth;J. Walsh;D. Buote;A. Baker;J. Darling;L. Ho
我们展示了~0.″10分辨率的阿塔卡马大型毫米/亚毫米阵列（ALMA）CO（2−1）成像，对巨型椭圆星系NGC 3258中的弧秒尺度（r ≈ 150 pc）尘埃分子盘进行成像。这些数据为超大质量黑洞（BH）动态影响范围内的冷气盘运动学提供了前所未有的分辨率，揭示了准开普勒中心增量预计旋转速度从盘外缘的 280 km s−1 上升到盘中心附近的 >400 km s−1。我们构建了旋转盘的动力学模型，并将光束涂抹模型 CO 线轮廓直接拟合到 ALMA 数据立方体。我们的模型结合了平环盘和倾斜环盘，可以更好地拟合 NGC 3258 中的轻微扭曲结构。我们表明，ALMA 数据出色的角分辨率使得仅从 ALMA CO 运动学推断主星系在 r = 150 pc 范围内的质量分布成为可能，而无需依赖光学或近红外成像数据来确定恒星质量分布。因此，我们的模型规避了由于星系中心区域的大量尘埃灭绝而导致的 BH 质量的任何不确定性。最佳模型拟合结果为 ，统计模型拟合不确定性仅为 0.18%，模型构建各个方面的系统不确定性为 0.62%，到 NGC 3258 的距离不确定性为 12%。这一观测结果表明 ALMA 在对包含核周气盘的早期型星系进行高精度测量方面具有全部潜力。
We present ∼0.″10 resolution Atacama Large Millimeter/submillimeter Array (ALMA) CO(2−1) imaging of the arcsecond-scale (r ≈ 150 pc) dusty molecular disk in the giant elliptical galaxy NGC 3258. The data provide unprecedented resolution of the cold gas disk kinematics within the dynamical sphere of influence of a supermassive black hole (BH), revealing a quasi-Keplerian central increase in projected rotation speed rising from 280 km s−1 at the disk’s outer edge to >400 km s−1 near the disk center. We construct dynamical models for the rotating disk and fit beam-smeared model CO line profiles directly to the ALMA data cube. Our models incorporate both flat and tilted-ring disks that provide a better fit of the mildly warped structure in NGC 3258. We show that the exceptional angular resolution of the ALMA data makes it possible to infer the host galaxy’s mass profile within r = 150 pc solely from the ALMA CO kinematics, without relying on optical or near-infrared imaging data to determine the stellar mass profile. Our model therefore circumvents any uncertainty in the BH mass that would result from the substantial dust extinction in the galaxy’s central region. The best model fit yields , with a statistical model-fitting uncertainty of just 0.18% and systematic uncertainties of 0.62% from various aspects of the model construction and 12% from uncertainty in the distance to NGC 3258. This observation demonstrates the full potential of ALMA for carrying out highly precise measurements of in early-type galaxies containing circumnuclear gas disks.