How do black holes interact with matter

Black holes: Matter at the point of no return

Cologne / Vienna. (est / dpa) Black holes are invisible cosmic objects whose gigantic gravity even light cannot escape. Anything that comes too close to a black hole is swallowed. At a certain point, all matter is irretrievably drawn inwards. Astronomers first observed matter at this "point of no return".

This brings them closer than ever to the supermassive black hole, which is believed to be in the center of the Milky Way. The observations are also taken as further confirmation of its long-suspected existence. The gravitational monster at the center of our galaxy is 26,000 light years from Earth and has a mass four million times that of the sun.

Matter that gets too close to a black hole is doomed to be dragged across the event horizon. The point closest to the black hole that the material can orbit is called the innermost stable orbit. This is where the gas compressions that have now been observed are located, as the European Southern Observatory (ESO) explains. According to their own statements, the scientists observed gas compressions that race around the black hole at 30 percent the speed of light. That corresponds to around 90,000 kilometers per second.

The international team used the "Gravity" instrument on ESO's Very Large Telescope (VLT) in Chile for their studies, which were published in the journal "Astronomy & Astrophysics". "Gravity" combines the light from the four VLT telescopes into a virtual super telescope with a diameter of 130 meters.

"It is overwhelming to actually witness how material moves around a massive black hole at 30 percent the speed of light," said Oliver Pfuhl from the Max Planck Institute for Extraterrestrial Physics (MPE).

At the beginning of this year, "Gravity" and another VLT instrument called "Sinfoni" made it possible for the same research team to precisely measure the flyby of the star S2 through the extreme gravitational field of the black hole in the center of the Milky Way. For the first time, the effects were demonstrated as predicted by Albert Einstein's general theory of relativity for such an extreme environment.

Infrared radiation registered

At the same time, the scientists registered strong infrared radiation. "During our observations we were lucky enough to notice three bright outbreaks around the black hole - it was a happy coincidence," said Puhl about the new observations.

According to the MPE, the movement of the three eruptions observed in the galactic center can be explained by the fact that the matter orbits the black hole in an orbit with a radius three to five times larger than the event horizon.

Study leader Reinhard Genzel from MPE explains: "It has always been one of our dream projects, but we didn't dare to hope that it would be realized anytime soon." The result of the research is "a convincing confirmation of the doctrine" that the huge object in the center of the Milky Way is a massive black hole.

"For the first time, matter around a black hole was observed so close to the point before it was swallowed," commented astrophysicist Josephine Peters from Oxford University, who was not involved in the study. "This is the beginning of a better understanding of humanity about the supermassive black hole at the center of the Milky Way."