Q&A: Black Holes
I was hoping you could tell me the date scientists confirmed
the presence of the black hole in the center of the Milky
In 1971 Donald Lynden-Bell and Martin Rees suggested that the
center of our galaxy should contain a supermassive black
hole. In 1974, Bruce Balick and Robert Brown found a compact
radio source there. This source came to known as Sagittarius
A* (Sgr A*) to distinguish it from more a extensive radio
source Sgr A in the same region. Infrared observations in the
1980s strengthened the case for a supermassive black hole.
The most recent breakthrough has been provided in the last 6
years by infrared images from the European Southern
Observatories' New Technology Telescope (A. Eckart and R.
Genzel) and the Keck Telescope (Andrea Ghez and
collaborators). These results suggest a black hole with a
mass of 2.6 million solar masses.
Recently (September 2001) Fred Baganoff and collaborators
used the Chandra X-ray Observatory to observe an X-ray flare
that brightened in about ten minutes provided more strong
evidence for a black hole. It is difficult to imagine any
other type of object that could flare up so brightly in so
short a time.