English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present the first Event Horizon Telescope (EHT) images of M87, usingobservations from April 2017 at 1.3 mm wavelength. These images show aprominent ring with a diameter of ~40 micro-as, consistent with the size andshape of the lensed photon orbit encircling the "shadow" of a supermassiveblack hole. The ring is persistent across four observing nights and showsenhanced 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 anestablished method (CLEAN) and a newer technique (regularized maximumlikelihood). This stage allowed us to avoid shared human bias and to assesscommon features among independent reconstructions. In the second stage, wereconstructed synthetic data from a large survey of imaging parameters and thencompared the results with the corresponding ground truth images. This stageallowed us to select parameters objectively to use when reconstructing imagesof M87. Across all tests in both stages, the ring diameter and asymmetryremained stable, insensitive to the choice of imaging technique. We describethe EHT imaging procedures, the primary image features in M87, and thedependence of these features on imaging assumptions.

First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole