Building the Event Horizon Telescope: Observing Black Holes with Schwarzschild Radius Resolution

在我们银河系的中心有一个巨大的黑洞，在其他星系的中心也有类似的物体，这些物体由于其巨大引力场的强度而扭曲了时空。在空间上，黑洞具有惊人的致密性。尽管如此，多尔曼博士和他的同事们利用分布在不同大陆的一组射电望远镜发出的毫米波无线电信号，将拍摄出黑洞的视界图像。高频和长干涉仪基线的结合将产生前所未有的高空间分辨率，该项目提出了一种科学上令人信服的利用方式。该项目将开发与目前用于洲际阵列的射电望远镜的毫米波和亚毫米波接收器相匹配的宽带甚长基线干涉测量(VLBI)仪器。通过将商用数字信号处理设备整合到定制系统中，将建造的仪器将在每个偏振中实现8 GHz的带宽。这种宽带宽对于最大化系统灵敏度至关重要。由此产生的VLBI网络将在1.3毫米波长下在天空实现数十微角秒的角分辨率。该团队早先的观测已经测量了银河系中心黑洞史瓦西半径尺度的结构，该项目计划观察和成像实际的黑洞事件地平线。根据该计划开发的硬件将向天文学社区提供。高中教师、本科生、研究生和博士后研究员将参与研究计划。将提供有价值的仪器操作培训，这些培训对其他现代射电望远镜也很有价值。该项目的资金由NSF的天文科学部通过其先进技术和仪器计划提供。

There is a massive black hole at the center of our galaxy, and similar objects at the centers of other galaxies, objects that distort spacetime by the strength of their immense gravitational fields. Spatially, a black hole is phenomenally compact. Nonetheless, Dr. Doeleman and his colleagues, utilizing the combined millimeter-wave radio signals from an array of radiotelescopes located on different continents, will image the event horizon of a black hole. The combination of high frequency and long interferometer baselines will produce an unprecedented high spatial resolution, and this project presents a scientifically compelling way to utilize it.The project will develop broadband very-long-baseline interferometry (VLBI) instrumentation matched to the millimeter- and submillimeter-wave receivers now in use at radiotelescopes suitable for use in the intercontinental array. With commercially available digital signal processing devices incorporated into custom systems, the instrumentation to be built will achieve 8 GHz of bandwidth in each polarization. That broad bandwidth is critical for maximizing system sensitivity. The resulting VLBI network will achieve, at 1.3 mm wavelength, tens of microarcseconds of angular resolution on the sky. Earlier observations by this team have measured structure on the scale of the Schwarzschild radius of the black hole at the center of our galaxy, and this project plans to observe and image the actual black hole event horizon.The hardware developed under this program will be made available to the astronomy community. High-school teachers, undergraduates, graduate students, and postdoctoral fellows will be involved in the research program. Valuable hands-on training in instrumentation will be provided that will be valuable on other modern radiotelescopes. Funding for this project is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.