# Event-Horizon-Scale Structure in the Supermassive Black Hole Candidate at the Galactic Centre

 Title: Event-Horizon-Scale Structure in the Supermassive Black Hole Candidate at the Galactic Centre Author: Doeleman, Sheperd S.; Weintroub, Jonathan; Rogers, Alan E. E.; Plambeck, Richard; Freund, Robert; Tilanus, Remo P. J.; Friberg, Per; Ziurys, Lucy M.; Moran, James M.; Corey, Brian; Young, Ken Harbour; Smythe, Daniel L.; Titus, Michael; Marrone, Daniel P.; Cappallo, Roger J.; Bock, Douglas C.-J.; Bower, Geoffrey C.; Chamberlin, Richard; Davis, Gary R.; Krichbaum, Thomas P.; Lamb, James; Maness, Holly; Niell, Arthur E.; Roy, Alan; Strittmatter, Peter; Werthimer, Daniel; Whitney, Alan R.; Woody, David Note: Order does not necessarily reflect citation order of authors. Citation: Doeleman, Sheperd S., Jonathan Weintroub, Alan E. E. Rogers, Richard Plambeck, Robert Freund, Remo P. J. Tilanus, Per Friberg, et al. 2008. “Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre.” Nature 455 (7209) (September 4): 78-80. doi:10.1038/nature07245. Access Status: Full text of the requested work is not available in DASH at this time (“dark deposit”). For more information on dark deposits, see our FAQ. Full Text & Related Files: moran-event-horizon.pdf (186.8Kb; PDF) Abstract: The cores of most galaxies are thought to harbour supermassive black holes, which power galactic nuclei by converting the gravitational energy of accreting matter into radiation. Sagittarius A* (Sgr A*), the compact source of radio, infrared and X-ray emission at the centre of the Milky Way, is the closest example of this phenomenon, with an estimated black hole mass that is 4,000,000 times that of the Sun. A long-standing astronomical goal is to resolve structures in the innermost accretion flow surrounding Sgr A*, where strong gravitational fields will distort the appearance of radiation emitted near the black hole. Radio observations at wavelengths of 3.5 mm and 7 mm have detected intrinsic structure in Sgr A*, but the spatial resolution of observations at these wavelengths is limited by interstellar scattering. Here we report observations at a wavelength of 1.3 mm that set a size of $$37^{+16}_{-10}$$ microarcseconds on the intrinsic diameter of Sgr A*. This is less than the expected apparent size of the event horizon of the presumed black hole, suggesting that the bulk of Sgr A* emission may not be centred on the black hole, but arises in the surrounding accretion flow. Published Version: doi:10.1038/nature07245 Other Sources: http://arxiv.org/abs/0809.2442 Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:33921646 Downloads of this work: