First Sagittarius A* Event Horizon Telescope results. III. imaging of the galactic center supermassive black hole

Kazunori Akiyama, ALBERDI ANTONIO, Walter Alef, Juan Carlos Algaba, F Richard, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislav Baloković, John P. Barrett, Michi Bauböck, Bradford Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L Bouman, Geoffrey Bower, Hope BoyceMichael Bremer, Christiaan Brinkerink, Roger Brissenden, Silke Britzen, Avery Broderick, BROGUIERE Dominique, Thomas Bronzwaer, Sandra Guadalupe Bustamante Gonzalez, Do-Young Byun, John Carlstrom, Chiara Ceccobello, Andrew Chael, Chi-kwan Chan, Koushik Chatterjee, S. Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Ilje Cho, Pierre Christian, Nicholas Conroy, James Cordes, CRAWFORD THOMAS, Geoffrey Crew, Alejandro Cruz-Osorio, Cui (崔玉竹) Yuzhu, Jordy Davelaar, Mariafelicia De Laurentis, Roman Gold, The Event Horizon Telescope Collaboration

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We present the first event-horizon-scale images and spatiotemporal analysis of Sgr A* taken with the Event Horizon Telescope in 2017 April at a wavelength of 1.3 mm. Imaging of Sgr A* has been conducted through surveys over a wide range of imaging assumptions using the classical CLEAN algorithm, regularized maximum likelihood methods, and a Bayesian posterior sampling method. Different prescriptions have been used to account for scattering effects by the interstellar medium toward the Galactic center. Mitigation of the rapid intraday variability that characterizes Sgr A* has been carried out through the addition of a “variability noise budget” in the observed visibilities, facilitating the reconstruction of static full-track images. Our static reconstructions of Sgr A* can be clustered into four representative morphologies that correspond to ring images with three different azimuthal brightness distributions and a small cluster that contains diverse nonring morphologies. Based on our extensive analysis of the effects of sparse (u, v)-coverage, source variability, and interstellar scattering, as well as studies of simulated visibility data, we conclude that the Event Horizon Telescope Sgr A* data show compelling evidence for an image that is dominated by a bright ring of emission with a ring diameter of ∼50 μas, consistent with the expected “shadow” of a 4 × 106 Me black hole in the Galactic center located at a distance of 8 kpc.
TidsskriftThe Astrophysical Journal Letters
Udgave nummer2
Antal sider64
StatusUdgivet - 10. maj 2022


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