Orbital configurations of spaceborne interferometers for studying photon rings of supermassive black holes

Abstract

Recent advances in technology coupled with the progress of observational radio astronomy methods resulted in achieving a major milestone of astrophysics - a direct image of the shadow of a supermassive black hole, taken by the Earth-based Event Horizon Telescope (EHT). The EHT was able to achieve a resolution of $\sim$20 $\mu$as, enabling it to resolve the shadows of the black holes in the centres of two celestial objects: the supergiant elliptical galaxy M87 and the Milky Way Galaxy. The EHT results mark the start of a new round of development of next generation Very Long Baseline Interferometers (VLBI) which will be able to operate at millimetre and sub-millimetre wavelengths. The inclusion of baselines exceeding the diameter of the Earth and observation at as short a wavelength as possible is imperative for further development of high resolution astronomical observations. This can be achieved by a spaceborne VLBI system. We consider the preliminary mission design of such a system, specifically focused on the detection and analysis of photon rings, an intrinsic feature of supermassive black holes. Optimised Earth, Sun-Earth L2 and Earth-Moon L2 orbit configurations for the space interferometer system are presented, all of which provide an order of magnitude improvement in resolution compared to the EHT. Such a space-borne interferometer would be able to conduct a comprehensive survey of supermassive black holes in active galactic nuclei and enable uniquely robust and accurate tests of strong gravity, through detection of the photon ring features.

Accepted for publication in Acta Astronautica. 40 pages, 13 figures

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Cited by in corpus (12)

• The Black Hole Explorer: Motivation and Vision
• Black hole bulk-cone singularities
• Gravity versus astrophysics in black hole images and photon rings: Equatorial emissions and spherically symmetric space-times
• Accurate analytical modeling of light rays in spherically symmetric spacetimes: Applications in the study of black hole accretion disks and polarimetry
• Assessing the impact of instrument noise and astrophysical fluctuations on measurements of the first black hole photon ring
• Effect of Earth's Oblateness on Black Hole Imaging Through Earth-Space and Space-Space VLBI
• Toward Optimisation of a Sub-Terahertz Spaceborne VLBI Mission
• Orbit design for mitigating interstellar scattering effects in Earth-space VLBI observations of Sgr A*
• Scattering of massive particles from black holes and naked singularities
• Lunar Time Ephemeris $\text{LTE440}$: definitions, algorithm and performance
• Extreme-Lensing Signatures Revealed by Correlations of Simulated Black-Hole Movies
• Shaving off soft hairs and the black hole image memory effect