05/23/2024 – 17:23
A team of astronomers studied powerful beams of light emitted by 16 black holes and discovered that some had changed direction. Cavities have been found in galaxies caused by them millions of years ago.
Scholars from institutions in the United States and Italy participated in the research. They used the Chandra X-ray Observatory, of the American Aerospace Agency (NASA), and the National Radio Astronomical Observatory (NRAO), of the National Science Foundation of the United States.
With Chandra X-ray, researchers spotted cavities where there should be hot gas at the center of a galaxy cluster Abell 478 and the NGC 5044 galaxy group. Both contain black holes that shoot beams of light. The cavities found were carved by light beams millions of years ago.
Images captured by the NRAO reveal where the beams point today from Earth. A comparison between the Chandra images and the NRAO images indicates that the black hole beams coming from Abell 478 changed their direction by 35º. In the case of NGC 5044, the change was twice as much.
Scholars believe that beams coming from black holes play an important role in the number of stars that will appear in the galaxy. Stars form from cold, dense molecular gases, but the beams inject energy into and around the galaxy.
This prevents it from cooling enough to form large numbers of new stars. By changing direction, the beams begin to suppress star formation in other areas.
Scientists observed that about a third of the 16 galaxies completely changed the direction in which they were pointing. In some cases, the displacement reached 90º, on time scales between one million and ten million years. As black holes are around 10 billion years old, changes in direction happen relatively quickly.
The beams result from matter falling into the spinning disc-shaped black holes as some of it is separated and redirected outward. The researchers believe that the direction of the beams – which are also likely rotating – aligns with the black holes’ axis of rotation.
They also assume that the beams are perpendicular, that is, they form a 90º angle, to the disk. If material falls into the black hole at a different angle that is not parallel to the disk, this can affect the direction of rotation of the black hole and therefore the light beams.
The article that described the results found was published in the January 2024 issue of the journal The Astrophysical Journal and can be accessed here.
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