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These foreign objects may have "seeded" supermassive black holes.

Dark stars

Astronomers have a new theory about the formation of supermassive black holes.

Extremely bright objects that first appeared near the birth of the universe, theoretical objects called "dark stars," could have sown supermassive black holes for millions of years, according to a new Astronomy history of physics at the University of Michigan Katherine Freese.

Dark stars would not have looked like the stars we are used to: instead of balancing gravitational forces with heat dissipated by nuclear fusion reactions, dark stars would have been much less dense, mostly composed of hydrogen and helium. That means they could have swollen to outrageous sizes compared to today's stars.

It is believed that the energy that prevented them from collapsing on itself came from particles of dark matter, which have not yet been directly observed, that annihilate each other, releasing energy in the process.

"They can continue to grow as long as there is dark matter fuel," said Freese. Astronomy. "We have assumed that they can obtain up to 10 million times the mass of the Sun and 10 billion times brighter than the Sun, but we really do not know. There is no cut in principle."

In 2016, for example, the Great Atacama Millimeter Set in northern Chile discovered a super massive black hole that was 660 million times more massive than the Sun.

Dark stars would have been anything but "dark." In fact, it is believed that they were much brighter than the Sun.

So why have astronomers not seen a dark star? The best assumption of astrophysicists is that they existed in the post-Big Bang era, and we still have to find a way to glimpse such an ancient stellar story.

But, luckily, NASA scientists are building a telescope sensitive enough so that one day they can see dark stars: the James Webb Space Telescope (JWST).

In a 2012 study, scientists from the Royal Astronomical Society at the University of Oxford proposed using the telescope to detect supermassive dark stars from the early stages of the universe. NASA astronomers also believe that JWST could allow us to glimpse the primitive cosmos.

"Searching for the first stars and black holes has long been an objective of astronomy," Rogier Windhorst of Arizona State University, Tempe, said in a statement from NASA in 2018.

And Reese also has hopes.

"If a dark star of one million solar masses were found [by James Webb] From very early on, it is quite clear that such an object would end up like a big black hole, "said Freese. Astronomy. “Then, these could come together to make supermassive black holes. A very reasonable scenario! "

While astronomers have been excited to begin studying JWST data, the project has unfortunately been in hell for more than two decades. In June 2018, the project was rescheduled for March 2021.

But if the JWST ever makes its way into space, it could provide new and attractive data about dark stars and supermassive black holes, and we would also be one step closer to understanding the first days of the universe.

READ MORE: Dark stars: The seeds of supermassive black holes?


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