Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre

By Sheperd S. Doeleman, J. Weintroub, A. Rogers, R. Plambeck, R. Freund, R. Tilanus, P. Friberg, L. Ziurys, J. Moran, B. Corey and 18 more. Nature, 2008

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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 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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/048cec389ba5a485ab67c90ad66376eef0036dcc

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Citations in the corpus

TESTING THE NO-HAIR THEOREM WITH EVENT HORIZON TELESCOPE OBSERVATIONS OF SAGITTARIUS A* (2013, methodology): “The currently available data for Sgr A* is comprised of observations during two days in 2007 (April 11 and 12, Doeleman et al. 2008) and three days in 2009 (April 5–7, Fish et al. 2011).”
The Event Horizon General Relativistic Magnetohydrodynamic Code Comparison Project (2019, positive): “Our own effort is motivated by the Event Horizon Telescope (EHT) project, which allows direct imaging of hot, luminous plasma near a black hole (hereafter BH) event horizon (Doeleman et al. 2008; Goddi et al. 2017; Event Horizon Telescope Collaboration et al. 2019a).”
Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole (2018, positive): “The radio source Sgr A* is coincident with the mass centroid to < 1 mas (Plewa et al. 2015), and is itself very compact, with R (1.3 mm)< 18 µas≈ 1.8 RS , based on millimetre very long baseline interferometry (Falcke et al. 2000; Doeleman et al. 2008; Johnson et al. 2017).”
Phenomenological aspects of black holes beyond general relativity (2018, background): “This continues to be true for more refined observations of the galactic center [109] that allow one to improve the constraint (17) by about three orders of magnitude.”
The size of the jet launching region in M87 (2011, methodology): “We use the new black hole mass source structure in Sgr A* on event horizon scales (Doeleman et al. 2008; Fish et al. 2011), allowing a direct comparison between observations and black hole accretion theory (e.g., Dexter et al. 2010; Broderick et al. 2011).”
HIGH-RESOLUTION LINEAR POLARIMETRIC IMAGING FOR THE EVENT HORIZON TELESCOPE (2016, background): “Future observations are expected to obtain enough data to construct an image of the SgrA* black hole accretion flow (Fish et al. 2014) and jet base of M87 (Lu et al. 2014).”
On the charge of the Galactic centre black hole (2018, background): “It can be either a Doppler beamed accretion flow or the footpoint of the jet (Doeleman et al. 2008; Dexter et al. 2012; Eckart et al. 2017) and in these cases it is difficult to make a connection to the charge of the black hole.”
Testing black hole candidates with electromagnetic radiation (2015, background): “Sub-millimeter very long baseline interferometry (VLBI) facilities should be able to resolve the shadow of SgrA∗ in the next few years (Doeleman et al., 2008).”
Electron Thermodynamics in GRMHD Simulations of Low-Luminosity Black Hole Accretion (2015, background): “The application of our methodology to Sgr A* is particularly important given the wealth of multi-wavelength data (e.g.,Serabyn et al. 1997, Zhao et al. 2003, Genzel et al. 2003, Baganoff et al. 2003, Barrière et al. 2014) and current and forthcoming spatially resolved observations with the Event Ho”
Black Hole Parameter Estimation from Its Shadow (2018, background): “Due to their relatively very large sizes and close proximity, the black hole candidates at the center of the Milky Way and in the nearby galaxy Messier 87, respectively, Sgr A* and M87*, are prime candidates for black hole imaging (Broderick & Narayan 2006; Doeleman et al. 2008, 2012).”