Researchers have discovered that the early universe contained far more black holes than previously thought, shedding new light on their formation and evolution. This finding could revolutionize our understanding of the cosmos’ earliest stages. Black holes are some of the most intriguing and powerful celestial objects, and their prevalence in the infant universe has significant implications for our cosmic history.
Unraveling the Mystery
Astronomers have been scratching their heads for years over what they call supermassive black holes, which are on the order of a billion times the mass of our sun. Even when the universe was younger than a billion years, we’ve seen these colossi at the centers of galaxies. The find has sparked interesting questions in the scientific community about how such massive objects could come into existence so soon after the Big Bang.
Earlier estimates suggested the early universe held only about a small number of black holes (SN Online: 2/22/18). But a new study reveals that there was something far more striking happening in the infant cosmos, published February 21 in The Astrophysical Journal Letters. This would allow us to maybe know how they are being born, as well as why are we observing them in a size that was not previously predicted.
Piecing Together the Origin of Black Holes
Theory (and hypothesis) predicts several ways black holes can take shape, most of which encounter problems.POSTSCRIPT. For example, they might consist of primordial black holes that formed shortly after the Big Bang. Still, this kind of process is expected to be rare and likely doesn’t explain the supermassive black holes seen in the young universe.
A competing theory says black holes have their origin in the collapse of massive stars at the end of stellar evolution. Stellar-mass” black holes like this should, in theory, be able to grow rapidly if they form in high-density star clusters where stars and black holes can collide. However, this process may not always work in explaining the presence of the monstrously large black holes witnessed eons ago present in the Universe.
A more probable answer is the birth of ‘heavy seeds’ — black holes weighing about 1,000 times more than previously identified massive stars. One route is through a process known as ‘direct collapse’, whereby the growth of the first dark matter structures stifled gas cooling, thereby discouraging their transformation into stars and causing them to fall directly into black holes. But this can explain only a tiny fraction of the black holes we see.
The Secrets of The Early Universe Revealed
The researchers then used more recent observations from the Hubble Space Telescope to command that the number of black holes in the early Universe was several times higher than what people have estimated. This is a major result that will be important for understanding the mechanisms of black hole formation and growth.
One possibility is that of ‘dark stars’ which could have been far smaller than black holes, and yet many times larger than ordinary stars, growing to a mass of 1,000 or more solar masses before collapsing. Theoretically, the “exotic” mechanisms could have been what created the vast black hole population seen in the baby universe.
With better and better views possible of the early universe thanks to new space-based telescopes now in operation — such as the James Webb Space Telescope, or soon to come like Euclid and Nancy Grace Roman Space Telescopes — it might be that we will see black holes being born right before our eyes, allowing us to more fully understand all aspects of these clever objects.
