Cosmic black holes have always been a big question for astronomers and space scientists. Understanding their origins can give us new insights into the universe, especially about the Big Bang.
According to Space.com, supermassive black holes in the universe formed surprisingly early, since the universe was less than a billion years old. Being formed at such an early time could disprove the theory that these black holes originated from the death of massive stars, which we have long believed. Instead, many scientists think that these supermassive black holes may have originated at the very first moment of the universe, the Big Bang.
As the name suggests, supermassive black holes are enormous in size. The smallest black holes are already millions of times more massive than the sun, while the largest ones – found at the centers of massive galaxies – are hundreds of billions of times more massive than the sun. When a massive star dies, it leaves behind a black hole a few dozen times the mass of the sun. That black hole “eats” the matter around it, finds other black holes and merges with them, and with luck, eventually achieves a supermassive state. Finding such massive black holes in the modern universe is not surprising, since those black holes have had billions of years to “eat” cosmic gas and dust and other black holes.
But recently, astronomers have begun to detect supermassive black holes in the early universe. Humanity has known more than 200 supermassive black holes existed when the universe was less than a billion years old and a supermassive black hole formed when the universe was only 700 million years old.
The problem is that this formation takes a long time, and these supermassive black holes appeared when the first stars and galaxies were forming. So where do they come from? According to scientists, perhaps the supermassive black hole in the universe does not originate from normal astrophysic processes, such as the death of stars and a stable diet of gas. Perhaps these massive black holes originate from the key early moments of the Big Bang.
The early universe was an extreme place with a density and pressure high enough to merge the fundamental forces of nature into unified fields. In those turbulent times, there can be extreme density contrasts that arise naturally. And in places of extreme density contrast – where a lot of mass is packed into a very small volume – black holes can form.
These are so-called primordial black holes, which are thought to have formed through strange interactions during the big bang. Astronomers have spent decades looking for them, especially through cosmic microwave probes, the light left over from when the universe was just 380,000 years old. While most did not yield positive results, they still found a reasonable hypothesis: Black holes with the mass of about 100,000 times the sun were formed in the first second of the Big Bang. Those black holes would quickly devour any surrounding matter, devouring themselves until they became the supermassive black holes we observe in the young universe. Observing and distinguishing between ancient and modern supermassive black holes is a challenge for our astronomy. The researchers emphasize that instruments such as NASA’s upcoming James Webb Space Telescope can meet the mission. This observation could not only reveal the origin of the supermassive black hole itself, but also provide astronomers with an invaluable opportunity to understand the earliest moments of the Big Bang.