Story about terrorists that destroy wormhole and leave planetary system isolated from rest of galaxy

Question

I am looking for a story that opens with a terrorist organization that destroys the only wormhole connecting a planetary system to the rest of the galaxy.

The story occurs centuries after humanity has contacted other civilizations in the galaxy and been accepted into the galactic community. Most inhabited planetary systems are connected to other planetary systems by one or more wormholes. The wormholes are large enough to allow spaceships to pass through.

The story opens in a distant star system with a few colonized worlds. The worlds are inhabited by humans and various alien species. A terrorist organization accelerates a city-sized rock from deep space up to near light speed. The rock's kinetic energy is about the same mass-energy equivalence as a gas giant planet. The rock impacts the only wormhole in the system and destroys it in a huge explosion.

The survivors are left completely isolated from the rest of the galaxy. One day they could send emails to their families or take a trip through the wormhole to the next nearest inhabited star system. The next day, they are alone.

They get a radio message after a few dozen years from a nearby star system. The message says another wormhole has been created for them and is being delivered now. Delivery will take over two centuries. This means they will never see their families again. They will never leave that planetary system for the rest of their lives.

Answer 1

This is The Algebraist by Iain M. Banks.

Per Goodreads

It is 4034. Humanity has made it to the stars. Fassin Taak, a Slow Seer at the Court of the Nasqueron Dwellers, will be fortunate if he makes it to the end of the year. The Nasqueron Dwellers inhabit a gas giant on the outskirts of the galaxy, in a system awaiting its wormhole connection to the rest of civilization. In the meantime, they are dismissed as decadents living in a state of highly developed barbarism, hoarding data without order, hunting their own young & fighting pointless formal wars. Seconded to a military-religious order he's barely heard of—part of the baroque hierarchy of the Mercatoria, the latest galactic hegemony— Taak has to travel again amongst the Dwellers. He is in search of a secret hidden for half a billion years. But with each day that passes a war draws closer—a war threatening to overwhelm everything & everyone he's ever known.

_{^{Algebraist - Blurb}}