Is there a Supermassive Black Hole at the Center of the Milky Way?

Abstract

This review outlines the observations that now provide an overwhelming scientific case that the center of our Milky Way Galaxy harbors a supermassive black hole. Observations at infrared wavelength trace stars that orbit about a common focal position and require a central mass (M) of 4 million solar masses within a radius of 100 Astronomical Units. Orbital speeds have been observed to exceed 5,000 km/s. At the focal position there is an extremely compact radio source (Sgr A*), whose apparent size is near the Schwarzschild radius (2GM/c^2). This radio source is motionless at the ~1 km/s level at the dynamical center of the Galaxy. The mass density required by these observations is now approaching the ultimate limit of a supermassive black hole within the last stable orbit for matter near the event horizon.

Invited review submitted to International Journal of Modern Physics D; 23 pages; 10 figures

References in corpus (6)

• Advection-Dominated Accretion and the Black Hole Event Horizon
• Testing the general relativistic ''no-hair'' theorems using the galactic center black hole SgrA*
• The structure of the nuclear stellar cluster of the Milky Way
• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• Production of Hypervelocity Stars through Encounters with Stellar-Mass Black Holes in the Galactic Centre
• Testing General Relativity with High-Resolution Imaging of Sgr A*

Cited by in corpus (16)

• First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
• The Proper Motion of Sagittarius A*: III. The Case for a Supermassive Black Hole
• The Size, Shape, and Scattering of Sagittarius A* at 86 GHz: First VLBI with ALMA
• Magnetic reconnection and plasmoid formation in three-dimensional accretion flows around black holes
• Discovery of Substructure in the Scatter-Broadened Image of Sgr A*
• Test of Einstein equivalence principle near the Galactic center supermassive black hole
• Adapting a Cryogenic Sapphire Oscillator for Very Long Baseline Interferometry
• The Galactic Center as a laboratory for theories of gravity and dark matter
• Constraints on Yukawa gravity parameters from observations of bright stars
• Persistent Non-Gaussian Structure in the Image of Sagittarius A* at 86 GHz
• Predictive model of fermionic dark matter halos with a quantum core and an isothermal atmosphere
• Observing a Black Hole Event Horizon: (Sub)Millimeter VLBI of Sgr A*
• Black Holes Admitting Strong Resonant Phenomena
• Testing black hole space-times with the S2 star orbit: a Bayesian comparison
• Observations of the 86 GHz SiO maser sources in the Central Parsec of the Galactic Centre
• Locating the VHE source in the Galactic Centre with milli-arcsecond accuracy