Increasing the amount of coverage in the uv-plane increases the quality of the image. Furthermore, the EHT only sparsely samples the Fourier domain of the image ( uv-plane) ( Event Horizon Telescope Collaboration 2019b), owing to the limited amount of suitable millimeter Very Long Baseline Interferometry (VLBI) telescope sites. The size of the Earth limits the resolution of the EHT. This mass estimate is computed from the observed angular size on the sky of 42 ± 3 μas ( Event Horizon Telescope Collaboration 2019a). 2018) and the mass is 6.5 ± 0.7 × 10 9 M ⊙ ( Event Horizon Telescope Collaboration 2019f). The distance to this SMBH is 16.8 ± 0.8 Mpc ( Bird et al. With this effective resolution, the EHT resolved the shadow of the black hole M 87 *, that is, a supermassive black hole (SMBH) in the nucleus of Messier 87. The EHT array consists of eight telescopes positioned all around the globe, resulting in an effective resolution of ∼20 microarcseconds ( μas) when operating at 1.3 mm ( Event Horizon Telescope Collaboration 2019b). Therefore, models of the accretion flow around black holes are needed to interpret the results of the EHT ( Event Horizon Telescope Collaboration 2019e). Although the scale of the observed shadow is on the order θ, the exact size depends on both the emission model and GR effects, such as spacetime rotation. This lensed image is known as the shadow ( Falcke et al. The event horizon is gravitationally lensed, resulting in an effective angular size of for a = 0, where D is the distance to the black hole. The event horizon defines a surface from within nothing can escape. The size of the black hole is set by its event horizon,, where R g ≡ GM BH/ c 2 is the gravitational radius. In this equation, J is the angular momentum of the black hole, G is the gravitational constant, and c is the speed of light. In GR, astrophysical black holes are characterized by their mass, M BH, and their spin. This image is direct evidence of the existence of black holes, a fundamental prediction of the general theory of relativity (GR Schwarzschild 1916 Kerr 1963). In April 2019, the Event Horizon Telescope (EHT) collaboration released the first image of the shadow of a black hole ( Event Horizon Telescope Collaboration 2019a, b, c, d, e, f). Key words: accretion, accretion disks / black hole physics / radiative transfer / methods: data analysis The expected resolution of space-based missions is higher than the current resolution of the Event Horizon Telescope, and we show that Deep Horizon can accurately recover the parameters of simulated observations with a comparable resolution to such missions. Since potential future space-based observing missions will operate at frequencies above 230 GHz, we also investigated the applicability of our network at a frequency of 690 GHz. We find that with the current resolution of the Event Horizon Telescope, it is only possible to accurately recover a limited number of parameters of a static image, namely the mass and mass accretion rate. The second network is a classification network that recovers the black hole spin a. The first network is a Bayesian deep neural regression network and is used to recover the viewing angle i, and position angle, mass accretion rate Ṁ, electron heating prescription R high and the black hole mass M BH. We trained two convolutional deep neural networks on a large image library of simulated mock data. We investigate the effects of a limited telescope resolution and observations at higher frequencies. In this work, we present Deep Horizon, two convolutional deep neural networks that recover the physical parameters from images of black hole shadows. Images like this can potentially be used to test or constrain theories of gravity and deepen the understanding in plasma physics at event horizon scales, which requires accurate parameter estimations.Īims. The Event Horizon Telescope recently observed the first shadow of a black hole. Max-Planck Institute for Radio Astronomy, Auf dem Huegel 69, 53115 Bonn, GermanyĬontext. Institut für Theoretische Physik, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, GermanyĪnton Pannekoek Instituut, Universiteit van Amsterdam, PO Box 94249, 1090 GE Amsterdam, The Netherlands Fromm 3 ,5 and Heino Falcke 1ĭepartment of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, The NetherlandsĮ-mail: for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY, 10010, USA Jeffrey van der Gucht 1, Jordy Davelaar 1 ,2, Luc Hendriks 1, Oliver Porth 4 ,3, Hector Olivares 3, Yosuke Mizuno 3, Christian M. Astronomical objects: linking to databases. Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes
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