“What came first, the galaxy or its monster black hole?”
Technically, this is a much older riddle than the riddle about the chicken or the egg; although we only became aware of this relatively recently. And according to new research, scientists may finally have an answer.
Supermassive black holes, which existed near the dawn of time, were long believed to shape the galaxies around them, accelerating the galaxies’ rates of star formation and thus influencing the evolution of the entire universe. But now, a reanalysis of data from the James Webb Space Telescope (JWST) shows that these black holes may have existed during the first 50 million years of our 13.8 billion-year-old universe, triggering star formation at such an early age.
Findings may challenge the idea that black holes only form after that The first stars and galaxies appeared.
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“We know that these monster black holes exist at the center of galaxies near the Milky Way, but the big surprise now is that they were also present at the beginning of the universe, almost like the building blocks or seeds of early galaxies,” Joseph said. Silk, team leader and professor at Johns Hopkins University, said in a statement. “They’ve really powered things up, like giant boosters of star formation, which is a complete reversal of what we thought was possible before, so much so that it could completely shake up our understanding of how galaxies form.”
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Silk points out that the distant and early galaxies that JWST has been looking at since it started sending data to Earth in the summer of 2022 are brighter than expected.
This suggests that galaxies are already filled with an unusually high number of stars and supermassive black holes; If true, this means our current theories about how galaxies grow may need revision.
“We argue that black hole outflow crushes gas clouds, turning them into stars and greatly accelerating the rate of star formation,” Silk said. “Otherwise, it’s very difficult to understand where these bright galaxies come from because they are generally smaller in the early universe. Why would they form stars so quickly?”
Currently, the most widely accepted theories of cosmic evolution suggest that early universe black holes were born when high-mass stars ran out of fuel supplies for nuclear fusion. In turn, these stars would collapse and form black holes later in the universe. This means that black holes must have arrived after the formation of the stars that gave birth to them and before the first accretion of galaxies.
But Silk and his colleagues discovered that black holes and galaxies coexisted in the ancient universe and influenced each other even 100 million years after the Big Bang. İpek says that if the history of the universe were compressed into a calendar year, this time period would only be equivalent to the first days of January.
crushing it in the early universe
The enormous gravitational pull of black holes means that nothing (not even light) can escape their outer boundary, known as the event horizon. What this means for us is that whatever is beyond the border cannot be seen directly.
But some things still happen beyond the event horizon. The gravity of a black hole is intense enough to create violent conditions for any surrounding matter with the misfortune of falling too close to the event horizon, heating it and causing it to flow brightly. This material can be swallowed or channeled to the poles of the black hole, where it can be ejected as jets or winds at speeds close to the speed of light.
Black holes actively feeding on material like this can power what are known as active galactic nuclei (AGN), or regions within galaxies that can outshine the combined light of every star in the galaxies.
Silk thinks this way of black holes acting like “cosmic particle accelerators” is what allowed JWST to detect so much in the early universe.
“We can’t clearly see these strong winds or jets very far away, but we know they must be present because we see many black holes in the early universe,” Silk explained. “These enormous winds from black holes crush nearby gas clouds and turn them into stars. This is the missing link that explains why the first galaxies were much brighter than we expected.”
The universe was going through a phase (or two)
The team behind this research theorized that the early universe had two distinct phases. In the first stage, high-speed outflows from black holes were seen, accelerating the birth of stars. When these exits ended, the second phase would begin.
Following this, when the universe was around a few hundred million years ago, huge gas clouds would be forced to collapse by violent magnetic storms caused by supermassive black holes. This may have triggered a new era of intense and rapid star formation, far surpassing the star birth rates seen in more modern galaxies.
Star formation would then be prevented because the massive flows from supermassive black holes would switch to an energy-saving state, cutting off the gas supply in galaxies where stars could form.
“We originally thought that galaxies formed when a giant cloud of gas collapsed,” Silk explained. “The big surprise was that there was a seed (a massive black hole) in the middle of that cloud, and that helped the interior of that cloud turn into stars at a much greater rate than we expected. And so the first galaxies are incredibly bright.”
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Not only do the team think future JWST data could provide more accurate counts of early stars and supermassive black holes that will confirm the new theory, the researchers also believe the $10 billion space telescope could provide some answers to fundamental questions closer to home.
“The real question is, what was our beginning? The Sun is one star in 100 billion in the Milky Way galaxy, and there’s a massive black hole in the middle. What’s the connection between the two?” İpek completed his words. “Within a year we will have much better data and will start to get answers to many of our questions.”
The team’s research was published in Astrophysical Journal Letters in January.