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EHT Spots Magnetic Flip at M87* as Shadow Holds Steady

Upgrades in 2021 lifted EHT sensitivity, enabling the first constraints on emission at the jet base.

Overview

  • A peer-reviewed multi-epoch analysis finds that the polarization pattern around M87* reversed between 2017 and 2021, with a weaker or stabilized signature in 2018.
  • The apparent ring size remained consistent across all epochs, reinforcing predictions for the black hole shadow from general relativity.
  • The expanded 2021 array, including Kitt Peak and NOEMA with improved short-baseline coverage and calibration, yielded the first EHT constraints on faint jet-base emission.
  • Researchers report rapid variability near the event horizon, with changes occurring on hour scales in the magnetized plasma.
  • The results were published September 16 in Astronomy & Astrophysics, and the collaboration plans higher-cadence observations, with continuous monitoring of M87* reported for next year.