An international team of astronomers has discovered an exceptionally fast-moving component within a powerful jet emanating from the supermassive black hole in Centaurus A, our nearest giant galaxy. The jet appears to be colliding with an unidentified object in its path, creating distinctive patterns in X-ray observations.
Published in The Astrophysical Journal | Estimated reading time: 5 minutes
A Cosmic Detective Story
Located approximately 12 million light-years from Earth, Centaurus A has long captivated astronomers with its spectacular jets that stretch across the entire galaxy. Using NASA’s Chandra X-ray Observatory over a 22-year period, researchers have uncovered a jet component moving at an astonishing speed – more than twice the speed of light in apparent motion.
The research team, led by David Bogensberger from the University of Michigan, analyzed over three decades of X-ray observations to track the movement of various bright spots, or “knots,” within the jet. One particular knot, designated as AX4, displayed unprecedented behavior.
“The structure of the jet in Cen A is likely better revealed in X-rays than in the radio band, which is usually used to investigate jet proper motions,” explains the research team in their paper.
Breaking Speed Records
The observations revealed that knot AX4 is moving at an apparent speed of 2.67 times the speed of light. This seemingly impossible speed is actually an optical illusion caused by the jet’s orientation relative to Earth, but it still indicates that the material is moving at least 94% of the speed of light – making it one of the fastest-moving objects ever observed in an external galaxy.
The team also discovered a mysterious V-shaped emission pattern, designated as C4, where the jet appears to be colliding with an unknown object. The two arms of this “V” stretch at least 700 light-years in length, creating a unique structure that has never been seen before in this galaxy.
Challenging Previous Understanding
These findings are forcing astronomers to reconsider their previous models of how galaxy jets behave. The extreme speed of AX4 contradicts earlier radio observations of the same region, suggesting that the X-ray and radio emissions may be tracing different structures within the jet.
Glossary
- Superluminal Motion: An optical illusion where objects appear to move faster than light due to their orientation relative to the observer, though they are actually moving slower than light speed.
- Jet Knots: Bright spots or clumps of material within a black hole’s jet, which can be tracked to measure the jet’s motion and behavior.
- Proper Motion: The apparent motion of an astronomical object across the sky as viewed from Earth.
Test Your Knowledge
How far is Centaurus A from Earth?
Centaurus A is located approximately 12 million light-years from Earth.
What is the apparent speed of knot AX4 in the jet?
AX4 displays an apparent speed of 2.67 times the speed of light (though this is an optical illusion).
Why do astronomers think the X-ray and radio observations show different structures in the jet?
The X-ray observations show much faster movement than radio observations of the same region, suggesting they are tracking different components of the jet structure.
What is the minimum actual speed of knot AX4 based on the observations?
The calculations show that AX4 must be moving at least 94% of the speed of light.
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