Some supermassive black holes found in giant elliptical galaxies become the source of colossal radio jets — powerful streams of charged particles ejected at nearly the speed of light. Such jets contain enormous amounts of radiation capable of changing the fate of their host galaxies.
While these jets are generally believed to exist only in elliptical galaxies, researchers have now discovered a spiral galaxy with colossal jets spanning an astonishing six million light-years.
This finding raises concerns as it suggests that our home, the Milky Way, which is also a spiral galaxy, could experience similar radiation in the future.
“It means the Milky Way could potentially create similar energetic jets in the future – with the cosmic rays, gamma rays, and X-rays they produce wreaking havoc in our solar system because of increased radiation and the potential to cause a mass extinction on Earth,” the study authors note.
A peculiar spiral galaxy
Using data from the Hubble Space Telescope and some other advanced instruments, the researchers studied a giant spiral galaxy (2MASX J23453268−0449256).
This galaxy is three times bigger than the Milky Way and houses a humongous black hole, which is billions of times heavier than our Sun.
The colossal jets are emitted by the black hole and influence various processes within and around the galaxy. For instance, 2MASX J23453268−0449256 has ample amounts of star-forming material in its surroundings, but the jets never let the material clump together.
“The galaxy is surrounded by a vast halo of hot, X-ray-emitting gas. While this halo slowly cools over time, the black hole’s jets act like a cosmic furnace, preventing new star formation despite the presence of abundant star-making material,” the study authors said.
Now you might be wondering, how it’s even related to the Milky Way. Well, our home galaxy also has a black hole at its center, which is four million times heavier than the Sun. Named Saggitarius A (Sgr A*), this black hole is currently inactive and does not shoot any jets.
However, if Sgr A* engulfs a star or a dwarf galaxy or some gas cloud falls into it, this black hole can also begin releasing powerful colossal jets. Such events have previously been observed in other galaxies where stars get ripped apart by black holes.
What happens next?
Once Sgr A* starts shooting colossal radio jets, this could disturb the energy flow in our galaxy, leading to one of the three possible outcomes.
The first possibility is that the jets change how gases, dust, and various other materials interact within and around our galaxy. This could influence star formation in certain parts of our galaxy.
A second outcome could be a sudden rise in genetic mutations on Earth driven by increased radiation. Species failing to adjust to these changes are likely to go extinct. However, even this is not the most grim possibility.
Intense colossal jets also have the power to destroy entire atmospheres on planets. On Earth, this could result in a damaged ozone layer, ending all life on our planet. “If Earth were exposed to a direct or nearby jet, it could degrade our ozone layer and lead to a mass extinction,” the study authors note.
Dark matter ensures stability
Despite housing a huge black hole and experiencing the most powerful colossal jets, 2MASX J23453268−0449256 has managed to remain intact, but how? According to the study authors, the answer to this question lies in its composition.
Compared to the Milky Way, the galaxy has 10 times the dark matter. The researchers suggest that this dark matter, in combination with the black hole, provides a balanced structure to 2MASX J23453268−0449256.
Therefore, “understanding these rare galaxies could provide vital clues about the unseen forces governing the universe – including the nature of dark matter, the long-term fate of galaxies, and the origin of life,” Shankar Ray, study co-author and a PhD candidate at Christ University, Bangalore, said.
The study is published in the journal Monthly Notices of the Royal Astronomical Society.