An article published in the journal “The Astrophysical Journal” reports the results of X-ray observations of the jets emitted by the supermassive black hole at the center of the Centaurus A galaxy. A team of researchers used NASA’s Chandra X-ray Observatory to find a V-shaped structure that indicates that one of the jets hit something whose nature is uncertain. Only Chandra’s X-ray observations revealed that unusual structure, cataloged as C4, while many other instruments, especially radio telescopes, had never shown such anomalies.
The Centaurus A radio galaxy is one of the first radio sources identified outside the Milky Way in 1949, and for this reason, it’s one of the most studied, especially in the radio band. The supermassive black hole at its center is surrounded by gas and dust and some of it isn’t swallowed but is ejected in jets that reach speeds close to the speed of light.
An article published in the journal “Nature Astronomy” in July 2021 showed the jets emitted by the supermassive black hole at the center of the Centaurus A galaxy in great detail using a combination of radio telescopes used by the Event Horizon Telescope (EHT) collaboration. Sometimes, certain phenomena are only visible in one electromagnetic band, and in this case, it was necessary to observe Centaurus A in X-rays to find an anomalous structure created by one of the jets hitting something along its path.
The X-ray source was cataloged as C4 because it’s the fourth structure candidate found in that area. It appears to have two streams of material that are moving apart at two distinct angles, giving it a V-shape at least 700 light-years long. This indicates that a jet from the supermassive black hole hit something, generating an X-ray emission and dragging material away from the object.
One hypothesis is that the object hit was a massive star. In this case, the X-rays could be generated by the collision of particles from the jet and gas from the stellar wind. That collision could generate turbulence that increases the density of the gas in the jet, which in turn generates the X-rays detected by Chandra. The V-shape is difficult to explain and could be related to the type of object hit. More information about the source would probably be needed, but at over 11 million light-years away, detecting sufficient detail is a challenge, to say the least.
This study shows how valuable observations are in different bands of the electromagnetic spectrum. In the case of the Centaurus A galaxy, there are structures visible only in the radio band and now possible structures visible only in X-rays have been reported, in particular, the one cataloged as C4. Follow-up observations could provide new information on the nature of C4 useful for understanding the consequences even thousands of light-years away of a supermassive black hole’s activity.
