用毫米波VLBI定域人马座A* 和M87
Localizing Sagittarius A* and M87 on Microarcsecond Scales with Millimeter VLBI
摘要：
随着事件视界望远镜（EHT）的出现，一种毫米/亚毫米甚长基线干涉仪（VLBI），它已经成为可能的图像与亚地平线分辨率的少数黑洞。然而，当不使用外部相位参考时，由于缺乏绝对相位信息，这些图像不会转换为微弧秒绝对位置。由于这些波长的大气相干时间很短，光源和相位参考之间的点头是不切实际的。然而，在这里，我们提出了一个替代方案，它利用的事实，即许多VLBI站内的EHT阵列在自己的权利。有了这个，我们表明，它应该是可能的绝对位置的超大质量黑洞在银河系中心（Sgr A*）和M87相对于附近的对象的精度约为1微弧秒。这是足以检测的扰动，以Sgr A* 的位置所造成的相互作用与恒星和恒星质量的黑洞在银河系的尖点上的一年的时间尺度，并严重限制天体物理相关的参数空间的轨道中等质量的黑洞，牵连在一些机制，产生年轻的大质量恒星在银河系中心。对于M87，它允许记录毫米图像，其中黑洞可以通过其轮廓与附近的发射来识别，以及现有的更大尺度的无线电图像，消除了无线电核心和倾斜度，开口角度和无线电喷流源的性质的模糊性。
英文摘要：
With the advent of the Event Horizon Telescope (EHT), a millimeter/sub-millimeter very-long baseline interferometer (VLBI), it has become possible to image a handful of black holes with sub-horizon resolutions. However, these images do not translate into microarcsecond absolute positions due to the lack of absolute phase information when an external phase reference is not used. Due to the short atmospheric coherence time at these wavelengths, nodding between the source and phase reference is impractical. However, here we suggest an alternative scheme which makes use of the fact that many of the VLBI stations within the EHT are arrays in their own right. With this we show that it should be possible to absolutely position the supermassive black holes at the centers of the Milky Way (Sgr A*) and M87 relative to nearby objects with precisions of roughly 1 microarcsecond. This is sufficient to detect the perturbations to Sgr A*'s position resulting from interactions with the stars and stellar-mass black holes in the Galactic cusp on year timescales, and severely constrain the astrophysically relevant parameter space for an orbiting intermediate mass black hole, implicated in some mechanisms for producing the young massive stars in the Galactic center. For M87, it allows the registering of millimeter images, in which the black hole may be identified by its silhouette against nearby emission, and existing larger scale radio images, eliminating present ambiguities in the nature of the radio core and inclination, opening angle, and source of the radio jet.
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