By pinpointing the exact moment when a black hole launched fast- moving material from the region surrounding it, a University of Alberta astronomer has uncovered an important clue to how new galaxies are formed.
The interaction of material ejected, or “burped,” from black holes with other gasses in space is fundamental to the creation of new galaxies, but Gregory Sivakoff’s research studying how and when matter is ejected from the black hole gives insight to the origins of these processes.
“One of the greatest questions in astronomy today is how black holes affect the formation of galaxies,” Sivakoff said.
“Our research may give foundational insight into this evolution by offering an understanding on the processes in which material from around a black hole is launched away.”
By using ultra-sharp detection methods made possible by the Very Long Baseline Array (VLBA) telescope system, along with an x-ray timing satellite, Sivakoff was able to detect and study an outburst by a stellar black hole located 28,000 light years away from Earth.
“Essentially, if your eyes were as sharp as the VLBA is, you’d be able to see somebody standing on the moon with your own eyes. Because of this, we were able to track how the jet’s behavior was changing,” Sivakoff explained.
“In our observations, we can see the emission blobs moving from the base of the black hole outwards at about the quarter the speed of light. And because those things are moving out, we can essentially play the tape backwards and precisely, to plus or minus half a day, to determine when those blobs started their journey.”
By understanding when the matter was ejected, it’s also possible to extrapolate under which environments this ejection can take place.
As Sivakoff explains, before the ejection takes place, the material in the regions immediately surrounding the black hole, called the accretion disk, becomes unstable, heats up and becomes sucked into the hole. After that, there’s an ejection of material from the black hole at incredible speeds.
“This is sort of the foundational research in trying to understand how the accretion disk … and the jet burst are linked,” Sivakoff said.
“By pinpointing exactly when the jet was launched, we can tell exactly what was going on in the accretion disk and we saw that the behavior was fundamentally changing. That means that we have a great meter to understand the physics of a projectile launch.”
Sivakoff’s research will help the astronomical community better understand the physics of how matter in the universe interact with each other.
While the exact mechanisms of the ejection remains mysterious to the scientific community, the launches also occur in supermassive black holes — similar to one at the centre of the Milky Way — which could have a significant impact in the creation of new galaxies.
“We’re not entirely sure what the material is inside the jet. It definitely includes electrons, but we don’t know if there are protons or positrons mixed in there,” Sivakoff said. “What we do know is that it’s some sort of ionized gas. As that material impacts other gasses in the future, it may affect how stars are formed.”
According to Sivakoff, more theoretical work will be done in the upcoming years in order to understand the full implications of the launch.
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