Detection of the Intrinsic Size of Sagittarius A* Through Closure Amplitude Imaging
Abstract
We have detected the intrinsic size of Sagittarius A*, the Galactic center radio source associated with a supermassive black hole, showing that the short-wavelength radio emission arises from very near the event horizon of the black hole. Radio observations with the Very Long Baseline Array show that the source has a size of 24 ± 2 Schwarzschild radii at 7-millimeter wavelength. In one of eight 7-millimeter epochs, we also detected an increase in the intrinsic size of \( \(60_{-17}^{+25}\%\) \). These observations place a lower limit to the mass density of Sagittarius A* of 1.4 × 104 solar masses per cubic astronomical unit.
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The National Radio Astronomy Observatory is a facility of NSF, operated under cooperative agreement by Associated Universities, Incorporated.
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Published In
Science
Volume 304 | Issue 5671
30 April 2004
30 April 2004
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American Association for the Advancement of Science.
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Received: 25 November 2003
Accepted: 22 March 2004
Published in print: 30 April 2004
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