Resolved magnetic-field structure and variability near the event horizon of Sagittarius A*
Publication information:
Michael D. Johnson, Vincent L. Fish, Sheperd S. Doeleman, Daniel P. Marrone, Richard L. Plambeck, John F. C. Wardle, Kazunori Akiyama, Keiichi Asada, Christopher Beaudoin, Lindy Blackburn, Ray Blundell, Geoffrey C. Bower, Christiaan Brinkerink, Avery E. Broderick, Roger Cappallo, Andrew A. Chael, Geoffrey B. Crew, Jason Dexter, Matt Dexter, Robert Freund, Per Friberg, Roman Gold, Mark A. Gurwell, Paul T. P. Ho, Mareki Honma, Makoto Inoue, Michael Kosowsky, Thomas P. Krichbaum, James Lamb, Abraham Loeb, Ru-Sen Lu, David MacMahon, Jonathan C. McKinney, James M. Moran, Ramesh Narayan, Rurik A. Primiani, Dimitrios Psaltis, Alan E. E. Rogers, Katherine Rosenfeld, Jason SooHoo, Remo P. J. Tilanus, Michael Titus, Laura Vertatschitsch, Jonathan Weintroub, Melvyn Wright, Ken H. Young, J. Anton Zensus, and Lucy M. Ziurys. 2015. “Resolved Magnetic-Field Structure and Variability Near the Event Horizon of Sagittarius A*”. Science, 350, Pp. 1242-45
Abstract
Near a black hole, differential rotation of a magnetized accretion diskis thought to produce an instability that amplifies weak magneticfields, driving accretion and outflow. These magnetic fields wouldnaturally give rise to the observed synchrotron emission in galaxy coresand to the formation of relativistic jets, but no observations to datehave been able to resolve the expected horizon-scale magnetic-fieldstructure. We report interferometric observations at 1.3-millimeterwavelength that spatially resolve the linearly polarized emission fromthe Galactic Center supermassive black hole, Sagittarius A*. We havefound evidence for partially ordered magnetic fields near the eventhorizon, on scales of ~6 Schwarzschild radii, and we have detected andlocalized the intrahour variability associated with these fields.