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Area of Science:

  • Astrophysics
  • General Relativity
  • Black Hole Physics

Background:

  • Black hole shadow size is mainly determined by mass and distance in general relativity.
  • Deviations from general relativity could significantly alter black hole shadow size.

Purpose of the Study:

  • To assess the capability of the Event Horizon Telescope (EHT) in measuring the angular radius of Sagittarius A*'s black hole shadow.
  • To investigate the potential for improving mass and distance measurements and constraining deviations from the Kerr metric.

Main Methods:

  • Utilizing a reconstructed image of Sagittarius A* from a simulated seven-station EHT observing run.
  • Employing a Markov chain Monte Carlo algorithm to analyze the shadow size.

Main Results:

  • Demonstrated the ability to measure the angular radius of Sagittarius A*'s shadow with an uncertainty of approximately 1.5 microarcseconds (6%).
  • Showed that EHT measurements can significantly improve existing mass and distance estimates.

Conclusions:

  • Upcoming EHT observations of Sagittarius A*'s shadow will provide precise measurements.
  • These measurements will yield tight constraints on potential deviations from the Kerr metric, testing general relativity in the strong-field regime.