![]() ![]() Our results provide direct evidence for the presence of a supermassive black hole at the center of the Milky Way, and for the first time we connect the predictions from dynamical measurements of stellar orbits on scales of 10 3-10 5 gravitational radii to event-horizon-scale images and variability. ![]() Our model comparisons disfavor scenarios where the black hole is viewed at high inclination (i > 50°), as well as nonspinning black holes and those with retrograde accretion disks. Using a large suite of numerical simulations, we demonstrate that the EHT images of Sgr A* are consistent with the expected appearance of a Kerr black hole with mass ~4 × 10 6 M ⊙, which is inferred to exist at this location based on previous infrared observations of individual stellar orbits, as well as maser proper-motion studies. The ring has modest azimuthal brightness asymmetry and a comparatively dim interior. A variety of imaging and modeling analyses all support an image that is dominated by a bright, thick ring with a diameter of 51.8 ± 2.3 μas (68% credible interval). The EHT data resolve a compact emission region with intrahour variability. These observations were conducted in 2017 using a global interferometric array of eight telescopes operating at a wavelength of λ = 1.3 mm. The EHT is also laying the groundwork for extended observing campaigns to make movies of jet launching in M87.We present the first Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A*), the Galactic center source associated with a supermassive black hole. The EHT is pushing toward observing at 345 GHz (0.87 mm), which will enable imaging at even higher angular resolution. In addition to these two sources, the EHT observes a wide range of AGN sources with prominent jets, ranging from radio galaxies to blazars, at a resolution unobtainable with any other instrument. Sgr A* has no obvious jet and is orders of magnitude smaller than M87 in mass and accretion rate. M87 is a low-luminosity active galactic nucleus (AGN) source that launches a jet that is prominent at radio and optical wavelengths. ![]() The two main targets for general relativity, M87 and Sgr A*, are very different in astrophysical character. The EHT also aims to understand the astrophysics of supermassive black hole systems. M87 and Sgr A* are the primary targets in which the photon ring is easily resolvable by the EHT. Confirming that the inner edge of the ring is circular and of the predicted size constitutes a test of general relativity in a strong-field environment. General relativity predicts that a bright photon ring will appear whose size is proportional to the mass of the black hole. The EHT aims to image the region affected by strong gravitational lensing around supermassive black holes. The Sparse Modeling Imaging Library for Interferometry (SMILI) has proven to be better than traditional imaging methods at reconstructing super-resolved images. Haystack is at the forefront in algorithms to turn calibrated data into images. Haystack is in the middle of a development program to modernize HOPS based on lessons learned from years of handling EHT data. Originally designed in the 1990s to handle geodetic VLBI data, HOPS has proven to be well suited to the challenges of reducing millimeter VLBI data. The main EHT data reduction pathway uses the Haystack Observatory Post-processing System (HOPS). Event Horizon Telescope observations were made by observations around the globe data was sent to MIT Haystack Observatory and the Max-Planck-Institut für Radioastronomie for correlation Algorithms ![]()
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