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Scientists map our galaxy’s black hole

Astronomers say they have confirmed that the center of our galaxy contains a supermassive black hole.
X-ray and radio images show the signature of the Milky Way's black hole. Streaks of radio-emitting matter known as the Galactic Center Radio Arc (shown in red) swirl around a source of X-ray emissions (shown in blue).
X-ray and radio images show the signature of the Milky Way's black hole. Streaks of radio-emitting matter known as the Galactic Center Radio Arc (shown in red) swirl around a source of X-ray emissions (shown in blue).
/ Source: Reuters

Scientists say they have confirmed that the center of our galaxy contains a supermassive black hole, a mysterious celestial object that sucks in everything around it, including light. By observing the orbit of a star around the invisible gravitational field, an international team of scientists has eliminated other possibilities of explaining the phenomenon.

“It is a great step forward,” said Reinhard Genzel of the Max-Planck Institute for Extraterrestrial Physics near Munich, who led the team. “We have been able to exclude some still possible alternative configurations. ... There is nothing left that one would consider realistic and possible, other than a black hole.”

Astronomers have been gathering information about black holes, which are detected by measuring their effect on nearby stars or the activity around their edges, for more than 20 years.

There has been growing evidence of a massive black hole, more than a million times the mass of the sun, in the center of our galaxy and other galaxies as well, but Genzel and his team believe their research is the best proof so far.

“Most astrophysicists would accept that the new data provide compelling evidence that a supermassive black hole exists in the center of the Milky Way,” said Alvio Renzini, a scientist at the European Southern Observatory in Chile.

Mysteries of the universe
Black holes, like the one in the center of the Milky Way, are thought to be the remains of dead quasars — the powerful, bright hearts of galaxies. Black holes have been described as the ultimate victory of gravity because of their ability to suck in stars and other galactic features.

Genzel and his team, whose research is reported in Thursday’s issue of the journal Nature, zeroed in on the black hole by analyzing 10 years of data and mapping nearly the entire orbit of a star called “S2” around the black hole.

“This is the only case we know of in all astronomy where such a star is so close and we can observe it. Most of the other stars have orbital periods between hundreds and millions of years,” Genzel said.

S2, which is seven times larger than the sun and must travel at phenomenal speed to avoid being sucked in by the black hole, has an orbit of about 15 years.

'Every big galaxy has a big black hole'
The scientists used the latest technology to study the orbit of S2. They said their measurements rule out a cluster of unusual stars or elementary particles to explain the dark mass and leave little doubt that it is a supermassive black hole.

“Now we know that every big galaxy has a big black hole and was probably formed at the same time and probably with some of the same processes which formed the galaxies themselves,” said Genzel.

“The next thing we all want to understand is, what were those processes which allowed these things to form so early, and were seeds in the young galaxies when they were formed?”