Black hole –The wonder of science and technology is that it enables us to discover new things, whether from our own planet or from the stars.
Astronomers have observed a stream of light coming from a distant region of the galaxy.
Scientists believe the light streak is the first indication of a massive black hole in motion.
As it extended, the black hole that appeared to be escaping its home galaxy was spotted leaving a path of budding stars and shocked gas.
If the indicators are correct, the celestial escape might aid scientists in solving the puzzle of what happens to black holes when galaxies collide.
While not being part of the study, Charlotte Angus from the University of Copenhagen praised the sighting.
“It’s a very cool, serendipitous discovery,” she said. “The possibility that this might be due to a supermassive black hole that’s been ejected from its galaxy is very exciting.”
“These events have been predicted by theory, but up until now, there’s been very little evidence for them.”
The researchers theorized that two dwarf galaxies collided about 8 billion years ago.
The resultant collision caused gas from the two galaxies to split off, leading in the formation of several new dwarf galaxies, including two devoid of dark matter.
Using the Hubble Space Telescope, astronomer Pieter van Dokkum and his colleagues searched for colliding dwarf galaxies.
They then discovered something unusual: a long straight line radiating from a faraway galaxy.
The line became brighter and smaller as it progressed through its streak.
“Whatever it is, we haven’t seen it before,” said van Dokkum from Yale University.
“Most astronomical objects are shaped like a spiral or a blob. There are not many objects that are just a line in the sky.”
When astronomers perceive lines, it is usually due to a moving object, such as a satellite, coming in the way of a telescope’s field of vision.
Pieter van Dokkum and his colleagues conducted follow-up observations at the Keck Observatory in Hawaii.
The measurements eventually revealed that the streak was associated with a galaxy whose light took almost 8 billion years (more than half the history of the universe) to reach Earth.
On February 9, the researchers published its findings in a paper submitted to arXiv.org.
The scientists were able to determine the length of the line at around 200,000 light-years, ruling out the possibility of a satellite.
“We considered a lot of explanations,” said van Dokkum.
“And the one that fit the best is what we’re witnessing is a massive object, like a black hole, moving very rapidly away from the galaxy.”
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Black holes are invisible on their own.
Yet, according to van Dokkum, a black hole does not depart a galaxy on its own.
Several stars and gases that were gravitationally linked to the black hole escape.
The gas will generate intense radiation that telescopes may detect.
The passage of the black hole through the gas and dust of the galaxy’s outer regions can compress some of the gas into new visible stars.
Another possibility is that the line represents a radiation jet launched by the galaxy’s center supermassive black hole.
Nonetheless, the scenario would most likely result in a narrow beam when flying close to the galaxy and a broad beam as it goes further away.
Meanwhile, the streak they discovered had the opposite effect.
If Pieter van Dokkum discovered a black hole, it might have been blasted from the center of the galaxy after colliding with one or two other neighboring blackholes.
A supermassive black hole is at the heart of nearly every galaxy.
As galaxies collide, their center black holes fuse as well.
If the conditions are favorable, the merger might provide a “kick” to the ensuing black hole, blasting it out at great speed.
Otherwise, the black hole was formed by the collision of three galaxies.
Three supermassive black holes compete for position as a third galaxy enters an ongoing merger.
One black hole is expected to be thrown from the cosmic smashup, while the other two travel slowly in the other direction.
Van Dokkum is more inclined to believe in a three-galaxy collision since there is evidence of a shorter, dimmer streak going in the opposite direction of the brilliant straight line.
More research needed
Experts will need to monitor the system more closely, maybe with the James Webb Space Telescope, according to Charlotte Angus, to establish it is an ejected supermassive black hole.
Further theoretical estimates of what runaway supermassive black holes should look like might also be beneficial.
Angus was inspired by the latest finding to go through old data for probable black hole streaks.
“I wonder if there are more of these features out there, sitting in someone’s data that might have just been missed.
Van Dokkum concurred, saying:
“Now that we know what to look for, these very thin streaks, it makes sense to go back to Hubble data.”
“We have 25 years of Hubble images that have not been searched with this purpose. If there are more to be found, I think we can do it.”
Image source: Science News