According to Levin, what surrounds Cygnus X-1?

According to Levin, what surrounds Cygnus X-1?

• A. Event horizon
• B. Accretion disk
• C. Magnetosphere
• D. Dust torus

Answer: (B)

In X-ray binaries like Cygnus X-1, material from a companion star is pulled toward the black hole but carries angular momentum. That means it can’t fall straight in; instead it forms a rotating disk around the hole—the accretion disk. As gas in this disk loses energy and spirals inward, it heats up to millions of degrees. The hot inner regions emit strong X-rays, which is why Cygnus X-1 shines brightly in X-ray observations. The event horizon is the boundary of the black hole itself, not a surrounding structure, so it isn’t described as something that surrounds the system. Magnetic fields can influence the flow and energy release, but the main, observable surrounding feature in this context is the accretion disk. A dust torus is a larger-scale structure more typical of some active galactic nuclei, not the immediate environment of a stellar-mass black hole in a binary.

In X-ray binaries like Cygnus X-1, material from a companion star is pulled toward the black hole but carries angular momentum. That means it can’t fall straight in; instead it forms a rotating disk around the hole—the accretion disk. As gas in this disk loses energy and spirals inward, it heats up to millions of degrees. The hot inner regions emit strong X-rays, which is why Cygnus X-1 shines brightly in X-ray observations.

The event horizon is the boundary of the black hole itself, not a surrounding structure, so it isn’t described as something that surrounds the system. Magnetic fields can influence the flow and energy release, but the main, observable surrounding feature in this context is the accretion disk. A dust torus is a larger-scale structure more typical of some active galactic nuclei, not the immediate environment of a stellar-mass black hole in a binary.