December 6, 2023

How can an isolated black hole travel through the Milky Way

Photo: NASA

wandering. Single. isolated. These are the definitions of a stellar black hole discovered drifting through the Milky Way.

Exactly, aimlessly, 5,000 light-years from Earth and at 160,000 kilometers per hour in the spiral arm of Carina-Sagittarius.

Like him, about 100 million nomadic beings of this type – unaccompanied by any stars – may be “travelling” through our galaxy.

According to NASA, the US space agency, the discovery of the first isolated black hole is the result of the analysis of two teams of researchers who for six years have studied the data captured by the Hubble Space Telescope.

One group, led by Kailash Sahu of the Space Telescope Science Institute, in Baltimore, with the participation of Brazil.

The other group is led by Casey Lamm of the University of California. Both used microgravity technology.

The technique consists in observing the amplification of the brightness of the background star (called the source), due to the passage of an object (called the lens) between the observer and the source. The lens distorts the spacetime around it and then the light from the source is deflected, increasing its brightness to the observer.

In this case, the black hole passing between the observer and the background star acted as a lens, and in addition to increasing the brightness of the source for more than 200 days (the period during which the event was observed), it also changed its position. Astrometry ‘, explains astrophysicist Leonardo Almeida, co-author of the study.

“I remember these small lenses well. They became so bright that it was possible to observe them with the smaller telescopes at the Pico dos Dias Observatory, located in Brazopolis, Minas Gerais. In the same year, we already suspected that the curve of those fine lenses might have been generated by A black hole, however, was necessary to measure the deflection of the light from the background star using astronomy.”

While the Berkeley team recognizes that it could still be a neutron star, according to a NASA statement, the unique signature in the star’s changing light could eliminate other potential gravitational lens candidates.

The study led by Sahu showed that the aberration caused by the lens as it passed in front of the star indicated an object with a mass seven times the mass of the Sun.

“The derived mass combined with no detection of glare from the lens suggests the presence of a possible lenticular object, a black hole of stellar origin. The mass of the black hole well supports models of stellar evolution for isolated objects. The black hole may also have been part of a binary system before it became nomadic.” It is located in our galaxy, so we can’t say for sure what the history of this object is. It proves once again that Albert Einstein’s theory was correct, but it also opens an important window for us to begin to better understand these things and the components of our Milky Way,” says Leonardo. Almeida.

stellar black hole

According to NASA, stellar-mass black holes have been known since the early 1970s, but all measurements of their masses – until now – have been in binary star systems. The gas from the companion star falls into the black hole and is heated to such high temperatures that it emits X-rays.

Source: Agência Brasil