Simulations of M87 and Sgr A* imaging with the Millimetron Space Observatory on near-Earth orbits
Simulations of M87 and Sgr A* imaging with the Millimetron Space Observatory on near-Earth orbits
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DOI：
10.1093/mnras/staa2709
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发表时间：
2020-06
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通讯作者：
A. Andrianov;A. Baryshev;H. Falcke;I. Girin;T. Graauw;V. Kostenko;V. Kudriashov;V. Ladygin;S. Likhachev;F. Roelofs;A. Rudnitskiy;A. R. Shaykhutdinov;Y. Shchekinov;M. A. Shchurov
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作者：
A. Andrianov;A. Baryshev;H. Falcke;I. Girin;T. Graauw;V. Kostenko;V. Kudriashov;V. Ladygin;S. Likhachev;F. Roelofs;A. Rudnitskiy;A. R. Shaykhutdinov;Y. Shchekinov;M. A. Shchurov
超大质量黑洞阴影的高分辨率成像是在极端重力条件下验证广义相对论的直接方法。超长基线干涉测量（VLBI）在毫米/亚毫米波长的观测可以为位于Sgr A*和M87的超大质量黑洞提供这样的角度分辨率。最近用事件视界望远镜（EHT）对M87的VLBI观测显示了这种能力。可获得的最大空间分辨率受地球直径和大气相位变化的限制。为了提高图像分辨率，需要更长的基线。Radioastron空间任务已经成功地证明了空间-地球VLBI基线比地球直径大得多的能力。“毫米波”是俄罗斯航天局的下一个太空任务，将在毫米波波段运行。天文台的标称轨道将位于日地系统的拉格朗日L2点附近。为了优化VLBI模式，我们考虑了使用近地高椭圆轨道（HEO）作为第二阶段任务的可能性。在此贡献中，一组近地轨道被用于在联合毫米和EHT配置下对Sgr a *和M87的综合空间-地面VLBI观测。利用Sgr A*和M87黑洞环境的广义相对论磁流体动力学模型（GRMHD）进行了230 GHz静态和动态成像模拟。地面基线和空-地基线的对比表明，与Millimetron和EHT的联合观测显著提高了图像分辨率，并使EHT+Millimetron能够在快速时间尺度上获得Sgr A*探测动态的快照图像。
High resolution imaging of supermassive black holes shadows is a direct way to verify the theory of general relativity at extreme gravity conditions. Very Long Baseline Interferometry (VLBI) observations at millimeter/sub-millimeter wavelengths can provide such angular resolution for supermassive black holes, located in Sgr A* and M87. Recent VLBI observations of M87 with the Event Horizon Telescope (EHT) has shown such capabilities. The maximum obtainable spatial resolution of EHT is limited by Earth diameter and atmospheric phase variations. In order to improve the image resolution longer baselines are required. Radioastron space mission has successfully demonstrated the capabilities of Space-Earth VLBI with baselines much larger than Earth diameter. Millimetron is a next space mission of the Russian Space Agency that will operate at millimeter wavelengths. Nominal orbit of the observatory will be located around Lagrangian L2 point of the Sun-Earth system. In order to optimize the VLBI mode, we consider a possible second stage of the mission that could use near-Earth high elliptical orbit (HEO). In this contribution a set of near-Earth orbits is used for the synthetic space-ground VLBI observations of Sgr A* and M87 in joint Millimetron and EHT configuration. General-relativistic magnetohydrodynamic models (GRMHD) for black hole environment of Sgr A* and M87 are used for static and dynamic imaging simulations at 230 GHz. A comparison preformed between ground and space-ground baselines demonstrates that joint observations with Millimetron and EHT significantly improve the image resolution and allow the EHT+Millimetron to obtain snapshot images of Sgr A* probing dynamics at fast timescales.