There is a supermassive black hole billions of times more massive than our sun at the center of almost every galaxy, including our own. The formation of supermassive black holes has puzzled astronomers for decades. There have been two theories regarding the formation of these monsters. One is that the supermassive black holes were born big and kept growing at a normal rate. The second idea is that they started small and grew at a rapid pace.
Supermassive black holes started small or big?
The “started big vs. started small” debate could not be settled, until now, because it was very difficult to find a black hole “seed” that is large enough to kickstart a supermassive black hole. On paper, it seems logical that the seeds started out small and grew bigger by merging with other black holes and pulling in gas from the surroundings. But there is a problem with the “started small” thesis.
You see, the first supermassive black holes appeared less than one billion years after the Big Bang that created the Universe about 14 billion years ago. No astronomer has been able to explain how the small black holes (with 10 to 100 times solar mass) could merge and grow fast enough to reach billions of solar masses in less than a billion years after the Big Bang.
Italian astronomers spot “seed” candidates
Now researchers at the Scuola Normale Superiore in Italy have been able to spot two black hole “seed” candidates using data from the Hubble Space Telescope, Chandra X-ray Observatory, and Spitzer Space Telescope. Lead author Fabio Pacucci said in a statement that their finding suggests the supermassive black holes start big and grow at a normal rate.
Both seed candidates are about 100,000 solar masses, and formed roughly a billion years after the Big Bang. The size and age of the seeds suggest that the supermassive black holes form “when a massive cloud of gas collapses.” It would allow them to start big and keep getting bigger. If a monster black hole is born out of a giant gas cloud, it could “skip” the early stages of growth.
Findings of the study were published in the Monthly Notices of the Royal Astronomical Society.