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Observations made by space telescopes have allowed scientists to better understand the cosmic giants that are black holes. Recently, a team of NASA astronomers made a fascinating discovery about one of the most mysterious galaxies: Centaurus A. Using the Chandra X-ray Observatory, researchers observed the spectacular interaction between the gigantic jets of plasma emitted by the supermassive black hole at its center and an unidentified object. The data collected could help improve our understanding of the evolution of galaxies.
Located in the constellation Centaurus, approximately 12 million light years from Earth, Centaurus A (NGC 5128) is one of the most enigmatic galaxies known. It intrigues scientists with its hybrid structure: a large dark band of dust and gas seems to bear witness to the ancient collision between a giant elliptical galaxy and a smaller spiral galaxy. This mixture gives Centaurus A a unique appearance, combining the typical characteristics of a massive elliptical galaxy and a spiral galaxy.
At the heart of this galaxy lies a supermassive black hole whose mass is estimated at 55 million times that of the Sun. This ejects particles and matter at speeds close to that of light, forming plasma jets that extend over vast distances. These emissions, visible in radio wavelengths, have fascinated researchers for decades. By studying Centaurus A with Chandra’s instruments, astronomers recently revealed a “V”-shaped region, whose arms are each about 700 light years away. These two branches converge on a light source of X-rays designated as C4.
According to scientists, C4, located in the path of the black hole’s jets, caused a shock wave accompanied by intense X-ray emissions. While researchers have a hypothesis about the phenomena at play, the exact identity of the struck object remains a mystery, because it is too far away for its details to be visible, even with the most powerful telescopes. », Indicates NASA in a press release.
The X-ray source of Centaurus A, called “C4”, seen in detail by Chandra. © NASA/CXC/SAO/D. Bogensberger et al.
An extraordinary phenomenon
Black holes, due to their extreme gravity, capture light and matter in their immediate vicinity, forming a rotating accretion disk. However, some of this material is expelled as colossal jets that extend vast distances, as shown by observations of Centaurus A. Although scientists have a comprehensive understanding of how these jets form, the exact nature of the object struck by the jet remains uncertain.
According to the results of the study, published inThe
Astrophysical Journaland led by Dr. David Bogensberger, an astrophysicist at the University of Michigan, the object in question could be a massive star. However, the capabilities of current observatories do not allow us to discern the details of this object. The X-ray emissions associated with C4 also appear to be atypical.
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Unlike other obstacles encountered by jets, which typically produce elliptical spots, C4 exhibits unusual characteristics. “These X-rays could result from a collision between the particles of the jet and a gas blown by a wind in the opposite direction to that of the star“, say the researchers. Such an interaction would have generated turbulence, increasing the density of the gas in the jet and thus causing these light emissions.
The V shape of this structure also intrigues astronomers. On the lower arm of the V, the X-rays appear to align parallel to the jet, like a wake left by a boat going upstream. On the other hand, the upper arm, more flared, deviates clearly from the axis of the jet. “Astronomers are trying to understand why C4 displays this asymmetry after the collision. This could be related to the nature of the object hit or how the interaction occurred», concludes NASA.
