A jet that's shooting out from black hole at nearly the speed of light is smashing into a mysterious object that astronomers can't identify.
The supermassive black hole is at the centre of galaxy Centaurus A, and astronomers have noticed a strange V-shape feature caused by the jet hitting an unknown object along its path.
This feature was observed by the Chandra X-ray Observatory, which shows low-energy X-rays seen in pink, medium-energy X-rays in purple and the highest-energy X-rays in blue.
Black holes have jets?
Yes, black holes are known to fire out jets of material into space, generated as they consume cosmic matter that wanders too close.
Galaxy Centaurus A is about 12 million lightyears from Earth and is well-known to astronomers.
The supermassive black hole at its centre launches a jet of high-energy particles from intense gravitational and magnetic fields around it.
Its jet is so powerful, it's moving at nearly the speed of light.
A strange V-shaped structure named C4 caused by a jet from a supermassive black hole at the centre of galaxy Centaurus A smashing into an unknown object. Credit: Main image: NASA/CXC/SAO/D. Bogensberger et al; Image Processing: NASA/CXC/SAO/N. Wolk; Wide field composite: X-ray (Chandra): NASA/CXC/SAO/D. Bogensberger et al; X-ray (IXPE): NASA/MSFC; Optical: ESO; Image Processing: NASA/CXC/SAO/N. Wolk
A strange V-shaped structure named C4 caused by a jet from a supermassive black hole at the centre of galaxy Centaurus A smashing into an unknown object. Credit: Main image: NASA/CXC/SAO/D. Bogensberger et al; Image Processing: NASA/CXC/SAO/N. Wolk
While the black hole and its jet have been studied before, astronomers had never seen the strange V-shaped structure until now.
Called C4, the structure is found near the path of the jet coming from the supermassive black hole.
The arms of the 'V' are at least about 700 lightyears long, astronomers say, but they can't be certain what's causing the strange shape.
What they can say, is that the black hole jet must be smashing into some unknown object.
It's too distant to be identified by even the most powerful telescopes.
A strange V-shaped structure named C4 caused by a jet from a supermassive black hole at the centre of galaxy Centaurus A smashing into an unknown object. Credit: Main image: NASA/CXC/SAO/D. Bogensberger et al; Image Processing: NASA/CXC/SAO/N. Wolk; Wide field composite: X-ray (Chandra): NASA/CXC/SAO/D. Bogensberger et al; X-ray (IXPE): NASA/MSFC; Optical: ESO; Image Processing: NASA/CXC/SAO/N. Wolk
Close-up of the V-shaped structure, named C4 Credit: Main image: NASA/CXC/SAO/D. Bogensberger et al; Image Processing: NASA/CXC/SAO/N. Wolk
What could it be?
Astronomers say the object being smashed by the black hole jet could be a massive star, or even a binary star.
X-rays from C4 could be caused by a collision between the particles in the jet and the gas in a stellar wind – a stream of particles blowing out from the star into space.
But why is it forming a V shape?
A strange V-shaped structure named C4 caused by a jet from a supermassive black hole at the centre of galaxy Centaurus A smashing into an unknown object. Credit: Main image: NASA/CXC/SAO/D. Bogensberger et al; Image Processing: NASA/CXC/SAO/N. Wolk; Wide field composite: X-ray (Chandra): NASA/CXC/SAO/D. Bogensberger et al; X-ray (IXPE): NASA/MSFC; Optical: ESO; Image Processing: NASA/CXC/SAO/N. Wolk
Wide-field view of the jet from a supermassive black hole at the centre of galaxy Centaurus A. Credit: X-ray (Chandra): NASA/CXC/SAO/D. Bogensberger et al; X-ray (IXPE): NASA/MSFC; Optical: ESO; Image Processing: NASA/CXC/SAO/N. Wolk
Astronomers say the stream of X-rays trailing behind the source in the bottom arm of the V is almost parallel to the jet, but the other arm of the V is skewed away from the jet, and remains a mystery.
C4 has a V-shape in x-ray, while other objects being struck by the jet produce distinct blobs instead.
For now, the mystery remains.
The authors of the study are David Bogensberger (University of Michigan), Jon M. Miller (University of Michigan), Richard Mushotsky (University of Maryland), Niel Brandt (Penn State University), Elias Kammoun (University of Toulouse, France), Abderahmen Zogbhi (University of Maryland), and Ehud Behar (Israel Institute of Technology).
Read the full paper at arxiv.org/abs/2408.14078.