How Big Can a Black Hole Get?

In the early 1960s, astronomers discovered a monster.

Something in the constellation of the Virgin poured radio waves, but no counterpart in visible light was initially observed. This has changed when observers have used certain smart techniques to see a light blue “star” based on the exact position of the radio source. Finally, they were able to determine that this object, called 3C 273, was not at all a star, but rather something much more foreign located two billion light years from the earth.

To be visible through so large expanses of space, “the quasi-studded object” (Quasar for short) 3C 273 had to be extremely brilliant. Scientists finally settled on a black hole fueling a distant galaxy as the most likely engine for the ridiculous brightness of 3C 273. And it was not fair any black hole but a brobdingnagian positively, probably containing 900 million times the mass of our sun.

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Since then, we have found many more supermassive black holes. In fact, in the 80s, astronomers began to suspect that each Big Galaxy had a supermassive black hole in its center. Thanks to the observations of the Hubble spatial telescope and other installations, we now know that it is true – which means that there could be to a giant billion in the observable universe.

And they can become massive – very massive. Many have been found with a billion times the mass of the sun, and the most meat can be even higher than that.

This naturally raises the question: how much can you get?

Reply, however, becomes a little delicate. A theoretical upper limit could burst out mass measures for many black holes, but such observations are difficult and often count on indirect evidence and incomplete accounts of all involved physics. In this spirit, however, this approach suggests that the biggest black holes exceed a few tens of billions of solar masses – it is also heavy as a small galaxy! Only a handful of these ultra-realistic weights are known, and the uncertainties in their masses can be quite significant.

However, is it possible that some can be even greater? After all, in principle, a black hole could grow endlessly because these objects gain mass by eating everything that is too close; If you could somehow offer the whole universe as a meal, a black hole would consume it with pleasure.

But stacking the whole cosmos on the dinner plate of a black hole is not very realistic, of course. According to research published in the Monthly opinion from the Royal Astronomical Society: Letters In 2015, under physically possible conditions (but incredibly ideal), the theoretical upper limit for a black food and growth hole should be a huge 270 billion Solar masses! More likely, however, the largest that we will ever find will be closer to only about 50 billion.

The gap comes down to the proximity of an object to a black hole to be fired. Even the largest black holes are only a few tens of billions of kilometers – at a scale similar to the size of our solar system – which is tiny on the cosmic stadium. By far, you are perfectly safe from their severity. If a black hole of solar mass suddenly replaces our sun, we would have fatal problems – like death to death – but our fall would not be one of them; The earth and the other planets would continue in their orbits as if nothing changed. Likewise, our Galaxy Milky Way has a supermassive black hole called SGR A * (pronounced “Sagittarius a star”) which represents around four million solar masses. It is about 26,000 light years from us, but that makes us no distress.

It really means that it is rather rare than everything falls into a black hole – and even when it happens, the mechanisms are not simple. Most materials will not dive head down in the mouth of cosmic garbage. Instead, its orbital speed increases when it falls towards the black hole so that it swirls madly around the compact object. This captive question will form a flattened disc called accretion disk.

In the disc, the equipment closer to the orbit will faster than the material further. This generates an incredible friction, heating the disc to millions of degrees. Important that Hot Glows fiercely, which is a way of detecting black holes in the first place: although they are invisible, the effect they have on the nearby material can be seen, even clear through the universe, as with the 3C 273.

The disc can be so hot that the material inside can be blown away by the intense radiation. Discs can have powerful magnetic fields that can also keep the material away. Together, these effects limit the speed with which a black hole can eat: an overabundance of influence materials can ensure that the disc becomes so tall and warm that it pushes any questions of additional approach. This is called the eddington limit; Consider it as the speed with which a black hole can eat without – and forgive the Indelicacy, but an analogy is an analogy – vomiting it.

So it takes time for a black hole to grow. And time is limited: the universe had a finished start. At best, a black hole had 13.8 billion years – the age of the cosmos – to stuff ourselves – and the first evidence that we found for black holes dates from a few hundred years after this period, more limiting their cosmic food frenzy.

Taking into account these temporal limitations, the biggest black hole today should not exceed 270 billion times the mass of the sun. And it is only If all its raw materials run in the same direction as the spin of the black hole, which acts as a digestive aid, allowing the material to fall more quickly. If the black hole does not turn or if the material falls in the direction opposed to this rotation, the upper limit falls to the solar mass of $ 50 billion.

This smaller number is indeed in the stadium of the highest black holes that we have detected. Some, like that called your 618, seem to be a little bigger, but there is a lot of uncertainty in this number, and the lower limit is probably also a little fungible.

I hasten to add that despite all this detailed discussion on the way black holes are dinner on matter, they can also develop a different way, via cosmic cannibalism: when galaxies collide, their black supermassive black holes can possibly fall together and merge to become a unique, even larger hole. It’s a time saving! But really huge black holes are so rare – never the even rarer perspective of their fusion – it is unlikely that this would considerably extend the limits of the growth of the black hole.

We therefore do not expect to find a bigger one than those that we have already managed to measure. But the universe is smarter than us, and it is always possible that an even more colossal hole could exist. If this is the case, it will give astronomers a chance to do their favorite thing: come back to their hypotheses and try to understand what they missed, learning more about these giants in the process. In this way, our knowledge is developing and, hopefully, there is no higher limit for this.