On the prospects of imaging Sagittarius A* from space
Freek Roelofs, Heino Falcke, Christiaan Brinkerink, Monika Moscibrodzka, Leonid I. Gurvits, Manuel Martin-Neira, Volodymyr Kudriashov, Marc Klein-Wolt, Remo Til… 展开作者
Freek Roelofs, Heino Falcke, Christiaan Brinkerink, Monika Moscibrodzka, Leonid I. Gurvits, Manuel Martin-Neira, Volodymyr Kudriashov, Marc Klein-Wolt, Remo Tilanus, Michael Kramer, Luciano Rezzolla
备注：
4 pages, 4 figures, published in Proceedings IAU Symposium No. 342, 2018
发表信息：
Perseus in Sicily: From Black Hole to Cluster Outskirts. Proceedings of the International Astronomical Union, Volume 342, pp. 24-28, 2020
Very Long Baseline Interferometry (VLBI) at sub-millimeter waves has the potential to image the shadow of the black hole in the Galactic Center, Sagittarius A* (Sgr A*), and thereby test basic predictions of the theory of general relativity. We investigate the imaging prospects of a new Space VLBI mission concept. The setup consists of two satellites in polar or equatorial circular Medium-Earth Orbits with slightly different radii, resulting in a dense spiral-shaped uv-coverage with long baselines, allowing for extremely high-resolution and high-fidelity imaging of radio sources. We simulate observations of a general relativistic magnetohydrodynamics model of Sgr A* for this configuration with noise calculated from model system parameters. After gridding the $uv$-plane and averaging visibilities accumulated over multiple months of integration, images of Sgr A* with a resolution of up to 4 $μ$as could be reconstructed, allowing for stronger tests of general relativity and accretion models than with ground-based VLBI.
Prospects for Discovering Pulsars in Future Continuum Surveys Using Variance Imaging
在Dai等人（2016）中，我们开发了一种形式主义，用于从包含时间和频率信息的标准干涉无线电图像计算方差图像。方差成像与未来的无线电连续调查，使我们能够识别无线电脉冲星，并作为一个补充，传统的脉冲星搜索是最敏感的严格的周期性信号。在这里，我们进行模拟来预测我们可以在未来的连续调查中使用方差成像发现的卫星数量。我们表明，澳大利亚SKA探路者（ASKAP）的宇宙进化图（EMU）调查可以发现$\sim30$正常的恒星和$\sim40$毫秒恒星（MSP）超过和超过今天已知的数量，同样的，一个全天空连续调查与SKA-MID可以发现$\sim140$正常的恒星和$\sim110$ MSP与此技术。EMU和SKA-MID的方差成像将检测具有大占空比的双星，因此是在相对论双星系统中寻找MSP和双星的潜在工具。与目前在南半球银河系高纬度地区进行的脉冲星调查相比，EMU和SKA-MID的方差成像将更加灵敏，并将能够探测色散测量值在$\sim10$和100 cm $^{-3}$ pc之间的脉冲星。
All-Sky Ultra-Narrowband Spectral Imaging with the OVRO-LWA: Technosignature Constraints and Axion-Like Particle Prospects
California Institute of Technology（加州理工学院）；Owens Valley Radio Observatory, California Institute of Technology（加州理工学院欧文斯谷射电天文台）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Arizona State University（亚利桑那州立大学）
