Astronomers have identified more and more black holes in recent ...

[jenna1]

Astronomers have identified more and more black holes in recent years by using x-ray imaging. If black holes are supposed to be black and not emit light, where are the x rays coming from?
  a. The accretion disk is full of accelerating atoms, which emit electromagnetic radiation as they accelerate.
  b. The friction within the accretion disk heats the gas to very high temperatures, and the gas emits x rays according to its characteristic spectrum.
  c. Hawking radiation not captured by the black hole knocks out K shell electrons within the accretion disk and the matter emits characteristic x rays.
  d. Scientists suspect that many of the supposed black holes are indeed neutron stars that emit x-ray radiation.
  e. Gravitational waves coming from the black hole are thought to interact with matter in the accretion disk, exciting many of the atoms into producing x rays.

Question 2

Frame dragging is a complex consequence of general relativity. It can be simplified into a classical analog, however, demonstrated by which of the following situations?
 

a. A merry-go-round spins objects further from the center of rotation at faster linear speeds.
  b. A flamenco dancer's dress as she spins quickly a full turn.
  c. An elevator falling in a uniform gravitational field that has a hole in it to let light through.
  d. A rubber sheet with a heavy ball at rest and a rolling ball with its trajectory changed by the depression in the sheet.
  e. A figure skater in a spin moves her arms closer to her body and the rate of spin increases.

[peilian]

Answer to Question 1

b.
It has been well established that x rays are emitted by black holes. Scientists suspect that the radiation comes from superheated gas in orbit falling into the black hole.

Answer to Question 2

b.
The dress of a flamenco dancer as she does a spin is like the fabric of spacetime when dragging about a massive rotating body

[jenna1]

Thank you!

[peilian]

Always glad to help...