Detection of the Intrinsic Size of Sagittarius A* Through Closure Amplitude Imaging

2004/03/31 by Geoffrey C. Bower, H. Falcke, Heino Falcke +6 · 2 citations
Physics and Astronomy · #Accretion (finance) #Active galactic nucleus #Amplitude #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Black hole (networking) #Experimental and Theoretical Physics Studies #Galactic Center #Galaxy #Milky Way #Millimeter #Optics #Physics #Pulsars and Gravitational Waves Research #Sagittarius #Sagittarius A* #Schwarzschild radius #Solar mass #Supermassive black hole #Very Long Baseline Array #Wavelength #astro-ph

paper · pdf · doi:10.1126/science.1094023

Accepted for publication in Science. Includes the supporting online material that accompanies the main article, which describe further details of the analysis of this experiment

arxiv created 2004/03/31 · openalex publication_date 2004/04/06 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

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 \batchmode \documentclass[fleqn,10pt,legalpaper]article \usepackageamssymb \usepackageamsfonts \usepackageamsmath \pagestyleempty \begindocument \(60_-17⁺²⁵%\) \enddocument . These observations place a lower limit to the mass density of Sagittarius A* of 1.4 × 10 4 solar masses per cubic astronomical unit.

Citations

• Structure of Sagittarius A* at 86 GH[CLC]z[/CLC] using VLBI Closure Quantities
• The First Measurement of Spectral Lines in a Short-Period Star Bound to the Galaxy’s Central Black Hole: A Paradox of Youth
• Proper Motion of the Compact, Nonthermal Radio Source in the Galactic Center, Sagittarius A*
• The Discovery of Sgr A*
• Dynamical Constraints on Alternatives to Supermassive Black Holes in Galactic Nuclei
• Viewing the Shadow of the Black Hole at the Galactic Center
• Intrinsic Size of Sagittarius A*: 72 Schwarzschild Radii
• Stellar Dynamics in the Central Arcsecond of Our Galaxy
• Covariant magnetoionic theory -- I. Ray propagation

Cited by

• Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre
• THE PROPER MOTION OF THE GALACTIC CENTER PULSAR RELATIVE TO SAGITTARIUS A*