There are supermassive black holes. Are ultramassive black holes. How big can these weird objects grow? Well, there could be something even bigger than ultramassive: wonderful large black holes, according to the latest research.
Such hypothetical black holes – more than 100 billion times the mass of the Sun – have been explored in a new work called SLABs, an acronym meaning “Stupendously LArge Black holeS”.
“We already know that there are black holes on a wide range of masses, with a supermassive black hole of 4 million solar masses living in the center of our own galaxy,” said astronomer Bernard Carr of Queen Mary University in London.
“Although there is currently no evidence for the existence of SLABs, it is conceivable that they may exist and also reside outside galaxies in intergalactic space, with interesting observational consequences.”
Black holes have only a few broad categories of mass. There are black holes with a stellar mass; these are black holes that are around the mass of a star, up to about 100 solar masses. The next category up is the black intermediate table holes, and how big they get depends on who you’re talking about. Some say 1,000 solar masses, some say 100,000, and others say 1 million; whatever the upper limit, they seem to be quite rare.
Supermassive black holes (SMBH) are much, much larger, on the order of millions to billions of solar masses. These include the SMBH in the heart of the Milky Way, Sagittarius A *, at 4 million solar masses, and the most photogenic SMBH in the Universe, M87 *, at 6.5 billion solar masses.
The strangest black holes we’ve detected are ultramassive, with over 10 billion (but less than 100 billion) solar masses. These include an absolute beast that falls to 40 billion solar masses in the center of a galaxy called Holmberg 15A.
“However, surprisingly, the idea of SLABs has been largely neglected so far,” Carr said.
“We have proposed options for how these SLABs could be formed and we hope that our work will begin to motivate discussions between the community.”
The problem is that scientists don’t really know how big black holes form and grow. One possibility is that they form in their host galaxy, then grow larger and larger, gathering a lot of stars, gas and dust and colliding with other black holes as the galaxies merge.
This model has an upper limit of about 50 billion solar masses – this is the limit at which the prodigious mass of the object would require a disk of accumulation so massive that it would fragment under its own gravity. But there is also a significant problem: supermassive black holes were found in the early universe at masses too large to grow through this relatively slow process in the time of the Big Bang.
Another possibility is something called primordial black holes, first proposed in 1966. The theory is that the different density of the early universe could have produced pockets so dense that they collapsed into black holes. They would not be subject to the size constraints of black holes in collapsed stars and could be extremely small or, well, extraordinarily large.
The extremely small ones, if they ever existed, would probably have evaporated due to Hawking radiation by now. But the much larger ones could have survived.
So, based on the primordial model of the black hole, the team calculated exactly how big these black holes could be, between 100 billion and 1 quintilion (mass 18 zero) of solar masses.
The purpose of the work, the researchers said, was to consider the effect of such black holes on the space around them. We may not be able to see SLABs directly – black holes that are not materials that gather are invisible because light cannot escape their gravity – but massive invisible objects can still be detected depending on how they behave. the space around them.
Gravity, for example, curves space-time, which causes the light that travels through those regions to follow a curved path; this is called a gravitational lens, and the effect could be used to detect SLABs in intergalactic space, the team said.
Huge objects would also have implications for detecting dark matter, the invisible mass that injects much more gravity into the Universe than it should – based on what we can detect directly.
A hypothetical candidate of dark matter, weakly interacting massive particles (WIMP), would accumulate in the region around a SLAB due to the immense gravity, in such concentrations that they would collide and annihilate each other, creating a halo of gamma radiation.
And primordial black holes are themselves a candidate for dark matter.
“The SLABs themselves could not provide the dark matter,” Carr said. “But if it exists, it would have important implications for the early universe and make it plausible that primordial black holes could do so more easily.”
We also couldn’t resist calculating the size of a black hole of 1 quintillion of solar mass. The horizon of events will end with over 620,000 light-years. Uh. Stupendous.
The team ‘s research was published in Monthly notifications from the Royal Astronomical Society.