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

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • National Radio Astronomy Observatory Socorro
  • Massachusetts Institute of Technology
  • National Astronomical Observatory of Japan
  • Harvard University
  • CSIC
  • Max Planck Institute for Radio Astronomy
  • Academia Sinica - Institute of Astronomy and Astrophysics
  • University of Valencia
  • University of Arizona
  • East Asian Observatory
  • Nederlandse Onderzoekschool voor Astronomie
  • California Institute of Technology
  • Academia Sinica Taiwan
  • Institut de Radio Astronomie Millimétrique
  • Radboud University Nijmegen
  • Perimeter Institute for Theoretical Physics
  • University of Waterloo
  • Korea Astronomy and Space Science Institute
  • University of Science and Technology UST
  • University of Chicago
  • Cornell University
  • University of Amsterdam
  • CAS - Shanghai Astronomical Observatory
  • Chinese Academy of Sciences
  • Chalmers University of Technology
  • Graduate University for Advanced Studies
  • University of Naples Federico II
  • Goethe University Frankfurt
  • University of Pretoria
  • Rhodes University
  • Max Planck Institute for Extraterrestrial Physics
  • Universidad de Concepcion

Abstract

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 μas 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 μas. Folding in a distance measurement of gives a black hole mass of . 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.

Details

Original languageEnglish
Article numberL6
JournalAstrophysical Journal Letters
Volume875
Issue number1
Publication statusPublished - 10 Apr 2019
MoE publication typeA1 Journal article-refereed

    Research areas

  • black hole physics, galaxies: individual (M87), gravitation, techniques: high angular resolution, techniques: interferometric

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