从恒星运动学的SINFONI AO辅助积分场观测得到的半人马座A黑洞的质量
The mass of the black hole in Centaurus A from SINFONI AO-assisted integral-field observations of stellar kinematics
摘要：
利用恒星运动学的高分辨率积分场观测，确定了椭圆星系半人马座A（NGC 5128）的超大质量黑洞（BH）质量和核恒星轨道分布.这些观测是在欧洲南方天文台甚大望远镜上用SINFONI在近红外（K波段）获得的，使用自适应光学校正地球大气层的模糊效应。该数据具有0.17”FWHM的空间分辨率和>80的高S/N/光谱像元，从而可以可靠地提取恒星视线速度分布的形状。我们探测到清晰的低水平恒星旋转，这是相对于气体的反向旋转。我们将轴对称三积分动力学模型与数据进行拟合，以确定BH质量的最佳拟合值M_BH=（5.5+/-3.0）*10^7 Msun（3 sigma误差）和（M/L）_K=（0.65+/-0.15）太阳单位。这些值与以前从气体运动学中确定的值非常一致，特别是与我们自己发表的从相同数据中提取的值非常一致。这提供了一个最干净的气体与恒星比较BH确定，由于使用积分场数据的动力学示踪剂和由于一个非常好的解决BH球的影响R_BH~0.70”。我们得到一个准确的配置文件的轨道各向异性，我们仔细测试其可靠性，使用球形牛仔裤模型与径向变化的各向异性。我们发现在BH附近切向各向异性的增加，但这种影响的空间范围似乎仅限于表面亮度剖面中的R_BH而不是核心的R_b~3.9”，这与目前对二元BH冲刷机制的模拟的详细预测相反。要从这一观察中得出结论，需要进行更现实的模拟。
英文摘要：
We present a determination of the mass of the supermassive black hole (BH) and the nuclear stellar orbital distribution of the elliptical galaxy Centaurus A (NGC5128) using high-resolution integral-field observations of the stellar kinematics. The observations were obtained with SINFONI at the ESO Very Large Telescope in the near-infrared (K-band), using adaptive optics to correct for the blurring effect of the earth atmosphere. The data have a spatial resolution of 0.17" FWHM and high S/N>80 per spectral pixel so that the shape of the stellar line-of-sight velocity-distribution can be reliably extracted. We detect clear low-level stellar rotation, which is counter-rotating with respect to the gas. We fit axisymmetric three-integral dynamical models to the data to determine the best fitting values for the BH mass M_BH=(5.5+/-3.0)*10^7 Msun (3sigma errors) and (M/L)_K=(0.65+/-0.15) in solar units. These values are in excellent agreement with previous determinations from the gas kinematics, and in particular with our own published values, extracted from the same data. This provides one of the cleanest gas versus stars comparisons of BH determination, due to the use of integral-field data for both dynamical tracers and due to a very well resolved BH sphere of influence R_BH~0.70". We derive an accurate profile of the orbital anisotropy and we carefully test its reliability using spherical Jeans models with radially varying anisotropy. We find an increase in the tangential anisotropy close to the BH, but the spatial extent of this effect seems restricted to the size of R_BH instead of that R_b~3.9" of the core in the surface brightness profile, contrary to detailed predictions of current simulations of the binary BH scouring mechanism. More realistic simulations would be required to draw conclusions from this observation.
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