Scientists find black holes could grow to ‘unbelievably large’ sizes

A recent study suggests the possible existence of “insanely large black holes” or SLABS, even larger than the supermassive black holes already seen in the center of galaxies.

The research, led by Queen Mary Bernard Carr Emeritus Professor at the School of Physics and Astronomy, in collaboration with F. Kühnel (Münich) and L. Visinelli (Frascati), examined how these SLABs might form and the potential limits of their size.

While there is evidence for the existence of supermassive black holes (SMBHs) in galactic nuclei – with masses one million to ten billion times that of the Sun – previous studies have suggested an upper limit to their size. because of our current take on how these black holes form and grow.

The existence of even larger SLABS than this could provide researchers with a powerful tool for cosmological testing and improve our understanding of the early Universe.

Challenge existing ideas

It has been widely believed that SMBHs form in a host galaxy and reach their large size by swallowing stars and gases from their surroundings or by merging with other black holes. In this case, there is an upper limit, slightly greater than ten billion solar masses, on their mass.

In this study, the researchers propose another possibility for the formation of SMBH, which could escape this limit. They suggest that such SLABs could be “primordial”, forming at the beginning of the Universe and long before the galaxies.

Since “ primordial ” black holes do not form from a collapsing star, they could have a wide range of masses, including very small and incredibly large.

Professor Bernard Carr said: “We already know that black holes exist over a wide range of masses, with an SMBH of four million solar masses residing at the center of our own galaxy. Although there is currently none. evidence of the existence of SLAB, it is conceivable that they could exist and could also reside outside galaxies in intergalactic space, with interesting observational consequences. However, surprisingly, the idea of SLAB has been largely overlooked until now. “

“We have offered options on how these SLABs might form, and hope that our work begins to motivate discussions within the community.”

Understanding dark matter

Dark matter is believed to make up about 80% of the ordinary mass of the Universe. Although we can’t see it, researchers believe dark matter exists because of its gravitational effects on visible matter, like stars and galaxies. However, we still don’t know what dark matter is.

One of the potential candidates is primordial black holes. The idea of ​​their existence dates back to the 1970s when Professor Carr and Professor Stephen Hawking suggested that in the first moments of the Universe, fluctuations in its density could have caused certain regions to collapse into black holes.

“SLABs themselves could not provide dark matter,” said Professor Carr, “but if they exist, it would have important implications for the early Universe and make it plausible that lighter primordial black holes do. . ”