Supermassive black hole

A quiet monster lurks in the heart of M31, the Andromeda Galaxy.

Known as M31 Star, it's a black hole 100 million times the mass of the Sun and 25 times heavier than the black hole at the heart of the Milky Way.

Every large galaxy probably has a supermassive black hole, and many of them are quite bright.

The black hole itself is completely black.

It swallows up all the matter and energy that falls into it, and nothing can come back out.

But the black hole's gravity pulls in huge amounts of gas and dust, along with an occasional asteroid, star, or other large object.

This debris forms a disk around the black hole.

As material in the disk spirals closer to the black hole, it gets extremely hot, so it shines brightly.

If you approached a stellar-mass black hole, the gravitational pull on your feet would be vastly stronger than on your head, tearing you apart through a process sometimes called spaghettification.

Supermassive black holes have gentler tidal forces at their event horizons because their immense size spreads the gradient across larger distances, so an astronaut could theoretically cross the boundary without immediate harm.

Yet once inside, all paths through spacetime inevitably lead toward the singularity at the centre, a point of infinite density where our current understanding of physics breaks down.

Time moves differently near black holes, a phenomenon that scientists call gravitational time dilation.

Their rotation influences the structure of the accretion disk and the jets that emerge from near the event horizon.

Stellar-mass black holes often exist in binary systems with normal stars, making them easier to detect and study through the radiation from accreting material.

Supermassive black holes reside at the centres of most galaxies, including our own Milky Way.

These objects contain millions or even billions of times the mass of our Sun.

Oh.

Supermassive black hole.

A supermassive black hole?

Oh, wow.

Yeah.

In super scenes.

That, that was the worst supermassive black hole that I've ever seen.

Yeah.

Uh, you can look them up on the little black hole website and find out all sorts of things about them.

Uh, and one of them is, uh, there exists, uh, a category of, uh, what's called supermassive black holes.

Uh, I mentioned the black holes that are, uh, that come from stars, and I'll talk about that much more today.

But I don't think I'm gonna have a chance to talk about the supermassive black holes.

These are black holes that live in the centers of galaxies, uh, and can have masses, uh, of hundreds of thousands, millions, sometimes even billions of times the mass of the Sun.

So very massive, uh, black holes, uh, in the centers of galaxies, including our own galaxy, by the way.

And you may, uh, if they succeed in this, somebody's winning the Nobel Prize, uh, and so you may, uh, find out about it by reading in the paper five years from now or so.

Yes.

They could eat a lot of gas around them, they could get bigger.

And, you know, so that was the prevailing idea, that you would grow them from these light seeds, the stellar corpses, and you would make the supermassive black holes.

But then something interesting happened observationally.

People started finding these billion solar mass black holes further and further back in time, which meant that you did not have enough time in the universe to grow from these little seeds to those monsters.

It was a sky survey that was done from the ground, telescopes on the ground.

And they were finding these quasars.

Basically, quasars are actively feeding supermassive black holes, so just gobbling up all the gas.

So basically, the reason you see the light, they are very bright beacons.