Supermassive black hole

A giant black hole lives in space.

It is much bigger than a normal black hole. It can be millions of times heavier than our Sun.

Most big galaxies have one at their center.

Our own galaxy has one too. It is at the very middle of our home.

These giants grow by eating gas. The gas pulls toward the black hole. This can make the center of a galaxy very bright.

Scientists have even taken a real picture of one. They used a special tool to see it. It was found in a far away galaxy.

These huge objects are a big mystery. We are still learning how they form.

A supermassive black hole is a giant object in space.

It is much larger than other black holes. These giants can be millions or even billions of times heavier than our Sun. Most large galaxies have one at their center. Our own Milky Way galaxy has one too. We call it Sagittarius A*.

These black holes grow in a few ways. They can pull in gas from space. This is called accretion. This gas can make the center of a galaxy look very bright. They can also grow by merging with other black holes.

Scientists have even taken a real picture of one.

They used the Event Horizon Telescope to see it. This image showed a black hole in the Messier 87 galaxy.

How do they start? Scientists have many ideas. Some think they start from the death of massive stars. Others think huge clouds of gas might collapse directly into a black hole. These are called direct collapse black holes. We are still studying how these giants began.

A supermassive black hole is a giant object in space.

These objects are the largest type of black hole we know. They can have a mass that is millions or even billions of times the mass of our Sun. Most large galaxies have one sitting right at their center. Our own Milky Way galaxy has one called Sagittarius A*.

These giants are very different from smaller black holes. For example, the tidal forces near them are much weaker. A person at the edge would feel about the same pull between their head and feet as someone on Earth.

These black holes grow through a few different ways. One way is through accretion, which is when they pull in gas from space.

This gas can make the center of a galaxy look very bright. Another way they grow is by merging with other black holes. Scientists also think they might start from "seeds." These seeds could be the remains of huge stars that exploded. Some might even come from large clouds of gas that collapse directly into a black hole.

Learning about these objects took a long time. In 1963, Maarten Schmidt studied a bright object called 3C 273. He found it was moving away from Earth very fast. This showed the object was a quasar, which is a very bright center of a galaxy. In 1964, Edwin Salpeter and Yakov Zeldovich suggested that matter falling into a massive object could explain these quasars. Later, in 1974, Bruce Balick and Robert Brown discovered the radio source Sagittarius A*. This gave us the first real hint that a supermassive black hole lives in our own galaxy.

There are many amazing facts about these cosmic giants. A supermassive black hole is often defined as having a mass above 100,000 solar masses. Some are even called ultramassive black holes if they are larger than 100 million solar masses. The black hole in the Messier 87 galaxy is a famous example. In 1994, the Hubble Space Telescope saw gas orbiting Messier 87 at 500 kilometers per second. This helped prove a huge mass was hidden there. Some very large black holes, called SLABs, might have masses greater than 100 billion solar masses.

We can compare these black holes to things we see in our own sky. Just as the Sun is the center of our solar system, these black holes sit at the center of galaxies. They act like a heavy anchor that holds things in place. We can even see the way they affect light. In 2019, the Event Horizon Telescope gave us the first direct image of a black hole in Messier 87.

This was a huge moment for science. It showed us the dark shape of a giant that has been hidden for a long time.

A supermassive black hole is the largest class of black hole in the universe. These astronomical objects form when matter undergoes gravitational collapse. This process creates a spheroidal region of space where gravity is so strong that nothing can escape, including light. Most large galaxies possess a supermassive black hole at their center. For instance, our Milky Way galaxy contains a supermassive black hole known as Sagittarius A*.

These giants are much larger than stellar-mass black holes. They are typically defined as having a mass exceeding 100,000 solar masses. Some reach masses of billions of times that of our Sun.

Supermassive black holes have unique physical properties that distinguish them from smaller black holes. One major difference is the strength of tidal forces near the event horizon. The event horizon is the boundary around the black hole. For these giants, the tidal forces are significantly weaker. A person at the event horizon would feel a pull between their head and feet similar to the pull felt on Earth's surface. This happens because tidal force is inversely proportional to the square of the black hole's mass. In smaller black holes, these forces become much more intense much sooner.

It is also surprising to consider the density of a supermassive black hole. Density is the mass divided by the volume within the Schwarzschild radius. The Schwarzschild radius is the distance from the center to the event horizon. Because this radius is directly proportional to mass, the volume increases very quickly. In fact, the volume is proportional to the cube of the radius. This means the average density of a supermassive black hole can actually be less than the density of water. As the mass increases, the average density decreases.

Scientists have different theories about how these giants begin. They might start as "seeds" from the first stars. These seeds would be the remains of massive stars that exploded. Another theory involves the direct collapse of large gas clouds. These clouds could form a "quasi-star" that eventually collapses into a black hole. Some models suggest that metal-free gas clouds can collapse directly into a black hole. These are called direct collapse black holes. They might reach masses of 10,000 to 100,000 solar masses without ever being a star.

Once formed, these black holes grow through accretion and merging. Accretion is the process of pulling in nearby interstellar gas. As gas falls toward the black hole, it can power active galactic nuclei (AGNs) or quasars. Quasars are extremely bright and energetic objects. Black holes also grow by merging with other black holes. Some researchers suggest that the most massive black holes might be "stupendously large black holes," or SLABs. These could have masses greater than 100 billion solar masses.

The history of studying these objects is quite long. In 1963, Maarten Schmidt studied the radio source 3C 273. He discovered it was a quasar moving away from Earth at high speeds. In 1964, Edwin Salpeter and Yakov Zeldovich proposed that matter falling onto compact objects explained quasars. Later, in 1974, Bruce Balick and Robert Brown discovered Sagittarius A*. This provided the first evidence of a supermassive black hole in our own galaxy. In 1994, the Hubble Space Telescope observed gas orbiting the center of Messier 87. The gas moved at 500 kilometers per second, proving a huge mass was present.

Modern technology has finally allowed us to see these objects more clearly. In 2019, the Event Horizon Telescope Collaboration released the first direct image of a black hole. This image showed the black hole at the center of the galaxy Messier 87.

This was a landmark moment in astronomy. In 2020, Andrea Ghez and Reinhard Genzel won the Nobel Prize in Physics. They were honored for discovering the supermassive compact object at the center of our galaxy. These discoveries connect our understanding of gravity, light, and the very structure of galaxies.