are gravitational waves somehow connected with dark matter??
Yes, in the way that dark matter interacts via gravity. In this case, dark matter would create gravitational waves were it to interact.
I wouldn't say gravitational waves are "connected" with dark matter beyond the fact that dark matter interacts via gravity. Other than that they have no connection to each other.
Yes in the sense that they interact with gravity. As for detectable wave? No. The dark matter will create geodesics that affect how we see the gravity waves, but it won't create it's own that are detectable. Only super dense objects like black holes or neutron stars produce gravitational waves that we can detect and dark matter doesn't clump together from what we can tell.
You seem to have a misconception that where gravity is concerned dark matter is different from ordinary matter. It is not.
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