And Iain M Banks was an agent.

A collection of scientific observations which prove that we're living in the universe of the Culture novels.

Excession

Two and a half millennia ago, the artifact appeared in a remote corner of space, beside a trillion-year-old dying sun from a different universe. It was a perfect black-body sphere, and it did nothing. Then it disappeared.

Now it is back.

"A dark alien world, blacker than coal, has been spotted by astronomers." - bbc.co.uk

Matter

The average Nestworld was a great gathered crown of tangled tubes within tubes within tubes within tubes; a halo world tens of thousands of years old, millions of kilometres acress and set circumference-on to its local star

"A swarm of comets has been proposed to explain the erratic and non-repeating light variations seen in the star located nearly 1,500 light years from Earth in the constellation Cygnus the Swan. But no one really seems satisfied with the explanation" - phys.org

Against A Dark Background

Golter orbits a star which sits out in deep space, between galaxies

"The Boötes void (colloquially referred to as the Great Nothing)[1] is an enormous, approximately spherical region of space, containing very few galaxies." - Wikipedia