• DOI:10.1126/science.aac7087
• Corpus ID: 21730194

Resolved magnetic-field structure and variability near the event horizon of Sagittarius A*

@article{Johnson2015ResolvedMS,
  title={Resolved magnetic-field structure and variability near the event horizon of Sagittarius A*},
  author={Michael D. Johnson and Vincent L. Fish and Sheperd S. Doeleman and Daniel P. Marrone and Richard L. Plambeck and J. F. C. Wardle and Kazunori Akiyama and Keiichi Asada and Christopher Beaudoin and Lindy L. Blackburn and Raymond Blundell and Geoffrey C. Bower and Christiaan D. Brinkerink and Avery E. Broderick and Roger J. Cappallo and Andrew A. Chael and Geoffrey B. Crew and Jason Dexter and Matt Dexter and Robert W. Freund and Per Friberg and Roman Gold and Mark A. Gurwell and Paul T. P. Ho and Mareki Honma and Makoto Inoue and Michael Kosowsky and Thomas P. Krichbaum and James W. Lamb and Abraham Loeb and Ru-Sen Lu and David Macmahon and Jonathan C. McKinney and James M. Moran and Ramesh Narayan and Rurik A. Primiani and Dimitrios Psaltis and Alan E. E. Rogers and Katherine A. Rosenfeld and Jason SooHoo and Remo P. J. Tilanus and Michael Titus and Laura Vertatschitsch and Jonathan Weintroub and Melvyn C. H. Wright and K. H. Young and J. Anton Zensus and Lucy M Ziurys},
  journal={Science},
  year={2015},
  volume={350},
  pages={1242 - 1245}
}

• Michael D. Johnson, V. Fish, +45 authors L. Ziurys
• Published 3 December 2015
• Physics
• Science

Magnetic fields near the event horizon Astronomers have long sought to examine a black hole's event horizon—the boundary around the black hole within which nothing can escape. Johnson et al. used sophisticated interferometry techniques to combine data from millimeter-wavelength telescopes around the world. They measured polarization just outside the event horizon of Sgr A*, the supermassive black hole at the center of our galaxy, the Milky Way. The polarization is a signature of ordered magnetic fields generated in the accretion disk around the black hole. The results help to explain how black holes accrete gas and launch jets of material into their surroundings. Science, this issue p. 1242 Magnetic fields around the event horizon of a supermassive black hole have been probed. Near a black hole, differential rotation of a magnetized accretion disk is thought to produce an instability that amplifies weak magnetic fields, driving accretion and outflow. These magnetic fields would naturally give rise to the observed synchrotron emission in galaxy cores and to the formation of relativistic jets, but no observations to date have been able to resolve the expected horizon-scale magnetic-field structure. We report interferometric observations at 1.3-millimeter wavelength that spatially resolve the linearly polarized emission from the Galactic Center supermassive black hole, Sagittarius A*. We have found evidence for partially ordered magnetic fields near the event horizon, on scales of ~6 Schwarzschild radii, and we have detected and localized the intrahour variability associated with these fields.