Question

How can be the black holes be found in space and with the of what?

Answer 1

See first of all you need to know that B.Hs are invisible.

But their presence can be observed when a big soure of light is ear it i.e. A massive star.

And its a powerful source of gravity, so no doubt we can find its gravitational waves in the space.

Answer 2

there is general consensus that supermassive black holes exist in the centers of most galaxies. Despites it invisible interior the presence of a black hole can be inferred through its interaction with other matter and with EM radiation such as visible light