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

我们银河系的中心有一个巨大的黑洞，其他星系的中心也有类似的物体，这些物体通过其巨大的引力场的强度扭曲时空。 在空间上，黑洞非常紧凑。 尽管如此，多尔曼博士和他的同事将利用来自不同大陆的射电望远镜阵列组合的毫米波无线电信号，对黑洞的事件视界进行成像。 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，该项目提出了一种在科学上令人信服的利用方式。该项目将开发宽带超长基线干涉测量（VLBI）仪器，与目前适用于洲际阵列的射电望远镜中使用的毫米波和亚毫米波接收器相匹配。 通过将商用数字信号处理设备集成到定制系统中，待构建的仪器将在每个极化中实现 8 GHz 的带宽。 如此宽的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 毫米波长下实现数十微角秒的天空角分辨率。 该团队的早期观测测量了银河系中心黑洞史瓦西半径尺度的结构，该项目计划对实际的黑洞事件视界进行观察和成像。根据该项目开发的硬件将提供给天文学界。 高中教师、本科生、研究生和博士后将参与该研究项目。 将提供宝贵的仪器实践培训，这对于其他现代射电望远镜也很有价值。 该项目的资金由美国国家科学基金会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.