Formation of X-Ray Binaries Outside Black Holes

[Abtinnn]

Just curious...
I mean they don't form inside the event horizon, so how would they form outside? How does accretion do this?

 

[phyzguy]

Stars are formed in clusters, and a certain percentage of them end up in binaries. So a binary star system forms consisting of two main sequence stars. The more massive of the two main sequence stars evolves off the main sequence and collapses into a black hole. The other star is still a normal star and continues to orbit while the black hole pulls material from the normal star into an accretion disk around the black hole. The hot matter in the accretion disk emits X-rays, and you have an X-ray binary. The normal star and the accretion disk are all outside the event horizon.

 

[Abtinnn]

Stars are formed in clusters, and a certain percentage of them end up in binaries. So a binary star system forms consisting of two main sequence stars. The more massive of the two main sequence stars evolves off the main sequence and collapses into a black hole. The other star is still a normal star and continues to orbit while the black hole pulls material from the normal star into an accretion disk around the black hole. The hot matter in the accretion disk emits X-rays, and you have an X-ray binary. The normal star and the accretion disk are all outside the event horizon.

Thank you for your response.
Also, why is the jet perpendicular to the plane of the accretion disk?

 

[phyzguy]

Thank you for your response.
Also, why is the jet perpendicular to the plane of the accretion disk?

This is a much more difficult question. The formation of the jets is a topic of active research, so nobody knows for certain why they have the structure they do. You could start here.

 

[Abtinnn]

Cool!

Thanks a lot! :D