Newton's wake - Ken MacLeod

The Hard Rapture took Earth's best minds away. Now the rest are about to find out where they went ... Centuries ago, space settlers and soldiers fled to the stars from the sentient AI war machines that engulfed Earth. They colonised Eurydice, a planet whose rocks contain traces of its own war machines - some of which still guard a vast, enigmatic artefact on a remote tundra.

When an expedition raids this strange artefact, the Eurydiceans discover that they weren't the last survivors of humanity after all. Their leisured lifestyle is about to be disrupted by new arrivals for whom Eurydice is a prize worth fighting over.

And the long-dormant war machines are awakening ...

Newton's Wake is a stunning stand-alone space opera, charting the struggle for human survival in a universe dominated by post-human intelligence.