another black hole question...?

Question

how are x rays used to detect black holes?

i mean x ray telescope

Answer 1

Gas falling into a black hole tends to emit x-rays just before it falls in. This is because it's moving very fast, due to the strong gravitational field, the gas around it is moving at a slightly different speed, and the friction between the two bits of gas heats it up to such high temperatures (hundred million degrees) that it emits x-rays.

This doesn't always happen, but it usually happens because the gas falling in has excess angular momentum and energy that must dissipate before the gas can fall in.

Answer 2

The gravitational field around a black hole can be very steep. This means that the gravitational force at one end of an object can be very different than the force at the other end of the same object (tidal tension). This tends to pull the object apart.

Get close enough and this tidal effect could even tear atoms apart. To tear an atom apart releases a lot of energy and that energy shows itself as photons of very high energy: gamma rays and X-rays.

This does not mean that any X-ray source is a black hole, but by analysing X-rays, we get hints as to whether the energy could come from some other phemomenom or if it could come from a black hole.

By combining this with observations at other wavelengths, we can determine what kind of object is responsible for the X-rays.

Answer 3

As matter spirals into a black hole, it gains both kinetic energy and heat. Just prior to disappearing beyond the Event Horizon, the matter is glowing, emmitting radiation in many wavelengths, primarily X-rays. The X-rays go off in all directions (including falling into the Black Hole), and when we detect a strong X-ray source, dollars to donuts their source is a black hole.