A new study led by the University of Michigan reveals fascinating insights into how black holes shoot out powerful streams of high-energy particles, known as jets.
These jets, stretching over vast distances, are some of the largest structures in the universe.
They can even be bigger than the galaxies that host them!
Scientists have been using NASA’s Chandra X-Ray Observatory to observe the jet from a supermassive black hole in the galaxy Centaurus A. Chandra, which launched in 1999, can detect X-rays, allowing scientists to see these jets in a different light compared to telescopes that observe radio waves.
Over 20 years of X-ray data from Chandra revealed something new: jets don’t look the same in radio and X-ray wavelengths.
Until now, most researchers thought X-rays and radio waves were just showing the same details, which wasn’t very exciting.
But lead author David Bogensberger and his team have discovered differences that could be key to solving many mysteries about black hole jets.
The team used a computer program to closely analyze bright spots in the jet called “knots.” By tracking these knots, which seemed to be moving, the scientists could measure their speeds.
One knot, in particular, was astonishing—it appeared to be moving faster than the speed of light!
However, this is an illusion caused by how it’s positioned relative to Chandra on Earth. The actual speed of this knot was found to be at least 94% of the speed of light.
Interestingly, when a similar knot’s speed was measured using radio waves, it was only moving at around 80% of the speed of light. This difference suggests that radio and X-ray observations of knots capture different characteristics of the jet.
Another surprising discovery was the location of the fastest knot. In past radio observations, knots closer to the black hole were usually the fastest. But this study found the quickest knot in a middle region—not the closest or farthest from the black hole.
These findings show that there’s still a lot to learn about how jets behave in the X-ray range. According to Bogensberger, this highlights the need for more research to understand these powerful cosmic phenomena.
The team plans to use their new method to study other galaxies. Centaurus A, located about 12 million light-years away, is the closest black hole jet to Earth, making it ideal for testing their approach. In the future, the researchers hope to apply this method to jets in more distant galaxies and uncover even more secrets.
