High-resolution imaging of a black hole shadow with Millimetron orbit around lagrange point l2

Abstract

Imaging of the shadow around supermassive black hole (SMBH) horizon with a very long baseline interferometry (VLBI) is recognized recently as a powerful tool for experimental testing of Einstein’s General relativity. The Event Horizon Telescope (EHT) has demonstrated that an Earth-extended VLBI with the maximum long base (D = 10, 700 km) can provide a sufficient angular resolution θ ∼ 20 μas at λ = 1.3 mm (ν = 230 GHz) for imaging the shadow around SMBH located in the galaxy M87*. However, the accuracy of critically important characteristics, such as the asymmetry of the crescent-shaped bright structure around the shadow and the sharpness of a transition zone between the shadow floor and the bright crescent silhouette, both of order Δθ ∼ 4 μas, is still to be improved. In our previous paper we have shown that Space-Earth VLBI observation within a joint Millimetron and EHT configuration at the near-Earth high elliptical orbit (HEO) can considerably improve the image quality. Even more solid grounds for firm experimental validation of General relativity can be obtained with a higher resolution available within the joint Millimetron and EHT program at the Lagrangian point L2 in the Sun-Earth system with an expected imaging resolution at 230 GHz of Δθ ∼ 5 μas. In this paper we argue that in spite of limitations of L2 orbit, an adequate sparse (u, v) coverage can be achieved and the imaging of the shadows around Sgr A* and M87* can be performed with a reasonable quality.

Visualization of Black Hole Images

“…In the nearest future it would be possible to verify modified gravity theories by observations of astrophysical black hole with international Millimetron Space Observatory [39][40][41][42]. The event horizon of the Kerr-Newman black hole rotates as a solid body with (i. e., inde-Figure 8.…”

Effects of Earth’s Oblateness on Black Hole Imaging through Earth–Space and Space–Space Very Long Baseline Interferometry

“…Recently, there have been several mission concept studies in literature that investigated the scientific merits of having a space-based VLBI station (Fromm et al 2021;Kurczynski et al 2022;Likhachev et al 2022;Rudnitskiy et al 2022;Roelofs et al 2023;Trippe et al 2023). These merits are intimately tied to the "cartography" of the (u, v) plots, with larger baselines implying higher angular resolution and shorter baselines improving the density of the (u, v) plane.…”

“…It is therefore apparent that in order to continue improving the resolution and the Fourier plane (hereafter the (u, v)) coverage, future VLBI missions targeting black hole astrophysics must have a space-based component. Indeed, there have been several recent mission concept studies in this domain (Kudriashov et al 2019;Andrianov et al 2021;Johnson et al 2021;Kurczynski et al 2022;Likhachev et al 2022;Hudson et al 2023;Roelofs et al 2023;Rudnitskiy et al 2023;Trippe et al 2023). The space missions can be a single orbiter working in tandem with a ground-based station to produce very long baselines, leading to very high angular resolution.…”