• Mysterious Origins
• At the Center of the Galaxy
• The Possibilites

    Black holes with millions and even billions of solar masses are believed to occupy the centers or nuclei of many galaxies. Unlike stellar black holes, the origins of supermassive black holes and the evolution of galaxies remain a mystery because the nuclei of galaxies are often hidden from observation by dense dust and gas. 

    However, that does not stop us from reviewing how we believe supermassive black holes can be formed.

At the Center of the Galaxy

    In the nucleus of a galaxy, hundreds of millions of stars are densely clustered up as they orbit and spin around. All of these stars are traveling at various speeds and "every now and then" will crash into another star. If the stars collide into each other, chances are they will annihilate each other throwing out gas everywhere (like parts in a huge car crash). 

But if they are moving close enough to each other's velocity, their gravity would attract each other. The two stars would combine or coalesce or to form one massive star. 

From here, many things can happen:

The Possibilities

• The massive stars might coalesce with other massive stars to form a very massive star which sooner or later would collapse into a very massive black hole. With time, the very massive black hole would consume millions of stars and grow into a supermassive black hole. 

• The released stellar gas from the smashing of stars would collect together and form a huge cloud of dense stellar gas. New stars could form from this cloud. These new stars, more massive than before, would collide into other stars releasing even more stellar gas into the cloud. After many cycles, this cloud might become so dense as to collapse under its own gravity to form a supermassive black hole.

• Instead of collapsing, the gas cloud could form one very unstable supermassive star which would almost instantly collapse into a supermassive black hole.
  
  
• Or the supermassive black hole was already in the center of the galaxy to begin with. During the galaxy's early formation, the core could have undergone a catastrophic gravitational collapse creating a supermassive black hole.