First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole

By K. Akiyama, A. Alberdi, W. Alef, K. Asada, R. Azulay, A. Baczko, D. Ball, M. Baloković, J. Barrett, D. Bintley and 204 more. Astrophysical Journal, 2019

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We present measurements of the properties of the central radio source in M87 using Event Horizon Telescope data obtained during the 2017 campaign. We develop and fit geometric crescent models (asymmetric rings with interior brightness depressions) using two independent sampling algorithms that consider distinct representations of the visibility data. We show that the crescent family of models is statistically preferred over other comparably complex geometric models that we explore. We calibrate the geometric model parameters using general relativistic magnetohydrodynamic (GRMHD) models of the emission region and estimate physical properties of the source. We further fit images generated from GRMHD models directly to the data. We compare the derived emission region and black hole parameters from these analyses with those recovered from reconstructed images. There is a remarkable consistency among all methods and data sets. We find that >50% of the total flux at arcsecond scales comes from near the horizon, and that the emission is dramatically suppressed interior to this region by a factor >10, providing direct evidence of the predicted shadow of a black hole. Across all methods, we measure a crescent diameter of 42 +/- 3 mu as and constrain its fractional width to be <0.5. Associating the crescent feature with the emission surrounding the black hole shadow, we infer an angular gravitational radius of GM/Dc(2) = 3.8 +/- 0.4 mu as. Folding in a distance measurement of 16.8(-0.7)(+0.8) gives a black hole mass of M = 6.5. 0.2 vertical bar(stat) +/- 0.7 vertical bar(sys) x 10(9) M-circle dot. This measurement from lensed emission near the event horizon is consistent with the presence of a central Kerr black hole, as predicted by the general theory of relativity.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5e3cf973f7cdcf8c10fcc45a08859b29af2bf8db

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Citations in the corpus

Lensing by Kerr black holes (2019, neutral): “[6] Event Horizon Telescope Collaboration, K.”
Shadows and deflection angle of charged and slowly rotating black holes in Einstein-Æther theory (2019, background): “Very recently, the Event Horizon Telescope (EHT) Collaboration announced their first image concerning the detection of an event horizon of a supermassive black hole at the center of a neighboring elliptical M87 galaxy [1, 2].”
Black Hole Parameter Estimation from Its Shadow (2018, methodology): “Further, fitting geometric models to the observational data and extracting feature parameters in the image domain indicates that we see emission from near the event horizon that is gravitationally lensed into a crescent shape around the photon ring (Akiyama et al. 2019c, 2019d).”
The shape of the black hole photon ring: A precise test of strong-field general relativity (2020, neutral): “[21] Event Horizon Telescope Collaboration, K.”
Measurement of the spin of the M87 black hole from its observed twisted light (2019, methodology): “The deterministic part represents the slow temporal evolution of M87*, which is a quasi-static source (EHT Collaboration 2019e,f,g), when observed in the intervals of one day that separate the acquisitions of each of the two pairs of nights (5–6 April and 10–11 April) with a broad consistency.”