: Yes they suck matters but probably they transform : matter in gravitons.

Gravitons are a theoretical particle that carries the force of Gravity. No one has ever seen a graviton and even the theory is little sparse as to what properties they have.

To explain a little better. Electromagnetism is a fundamental force. We commonly see and use electromagnetic (EM) waves as visible light, radio, x-rays and other types of radiation. It is possible to think of an EM waves as real particles called photons. When two particles, two protons say, pass each and their EM fields interact they pass a photon between themselves. In this case the photon is a force carrier.

The force that holds neutrons, protons and the like together is called the Strong Nuclear force and its force carrier is the Gluon (a bad physics joke).

Gravity is a force and should have an associated particle as a force carrier, this is the graviton. The most exciting area of physics is the search for gravitons and the theories that are being put forward to investigate what they can do and how to detect them.

: But : Gravitons are a form of Energy.

energy and matter are interchangeable. This is the basis of the famous E=mc^2 equation. In english it says energy=mass time the speed of light squared, or energy is proportional to the amount of matter.

: : Then : B.H. are not sucking matter but they are transforming it in Energy : they attract ,transform and finally expel

Gravity is a result of spacetime being bent by a mass, such as a black hole. As the hole absorbs matter it bends spacetime more which we see as a greater gravitational field. This has nothing to do with the hole converting mass to energy and releasing it. Please remember that many black holes have now been detected, some as massive as ten million suns. This would mean prodigous quantities of gravitons are being produced by your ideas, they have not been detected, yet!

Dontcha just hate that.