First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
Name
The_Event_Horizon_Telescope_Collaboration_2019_ApJL_875_L4.pdf
Description
Published version
Size
20.32 MB
Format
Adobe PDF
Checksum (MD5)
fc82324513e36ef0148ca8076c0ce604
Author(s)
The Event Horizon Telescope Collaboration
Date Issued
2019
Journal
Astrophysical Journal Letters
Publisher
American Astronomical Society
Version
Final published version
Abstract
© 2019. The American Astronomical Society.. We present the first Event Horizon Telescope (EHT) images of M87, using observations from April 2017 at 1.3 mm wavelength. These images show a prominent ring with a diameter of ∼40 μas, consistent with the size and shape of the lensed photon orbit encircling the "shadow" of a supermassive black hole. The ring is persistent across four observing nights and shows enhanced brightness in the south. To assess the reliability of these results, we implemented a two-stage imaging procedure. In the first stage, four teams, each blind to the others' work, produced images of M87 using both an established method (CLEAN) and a newer technique (regularized maximum likelihood). This stage allowed us to avoid shared human bias and to assess common features among independent reconstructions. In the second stage, we reconstructed synthetic data from a large survey of imaging parameters and then compared the results with the corresponding ground truth images. This stage allowed us to select parameters objectively to use when reconstructing images of M87. Across all tests in both stages, the ring diameter and asymmetry remained stable, insensitive to the choice of imaging technique. We describe the EHT imaging procedures, the primary image features in M87, and the dependence of these features on imaging assumptions.
MIT Department
Haystack Observatory
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Terms of Use
Creative Commons Attribution 3.0 unported license
Persistent DSpace Link
DOI of Published Version
10.3847/2041-8213/ab0e85
https://doi.org/10.3847/2041-8213/ab0e85
