chsham asks;I hope someone who is a expert in this topic can answer me ? If yes,I`ll feel happy.

Of course I am no expert, but you seem to insist that the graviton be recognized; which got me searching for more.
The best I could find on the web came from fermilab`s public affairs office. Here is The complete text on gravitons by Glenn Blanford (blanford@fnal.gov) I found at that site.
Here also are a few lines from that same text.

I believe that Mr. Blanford even answered your basic question when he said...Large mass objects such as black holes may emit waves. These are not neccessarily gravitons just as light was not neccessarily seen as photons until high energy light such as X-rays were seen. (ie The X-rays act like small size particles sometimes more than they do as waves).And of course here are some other links that I hope will work for you.