But on larger scales, the internal motions of individual galaxies indicate the presence of more mass than we observe. Galaxies in clusters move around too quickly, while X-rays reveal an insufficient amount of normal matter. ... Gravitons are undefined as is dark matter. We know dark matter has gravity.

Is graviton a matter?

In string theory, believed to be a consistent theory of quantum gravity, the graviton is a massless state of a fundamental string. ... If it exists, the graviton is expected to be massless because the gravitational force has a very long range, and appears to propagate at the speed of light.

Is a black hole a graviton?

In this sense the black hole is a kind of "frozen star": the gravitational field is a fossil field. ... If things like gravity correspond to the exchange of "particles" like gravitons, how can they get out of the event horizon to do their job? Gravitons don't exist in general relativity, because GR is not a quantum theory.