Noise floor for various detectors. Spikes are from mechanical vibrations in parts of the detector and multiples of the electric power line frequency. post 
Laser interferometers around the world have been listening for weak signals from cosmic events for decades. So far they are more interesting for how they work than what they have found.
On September 18, 2015, Advanced LIGO became fully operational and began formal science operations at twice the sensitivity of the initial interferometers. wikipedia
"The one thing I personally like about Ligo is it's used every bit of physics I know, from the most arcane solid-state and surface physics to lasers, electronics, quantum mechanics - everything," said Vern Sandberg, the lead scientist at the Hanford lab. bbc
Within weeks after a 200 million dollar upgrade at Hanford, Washington, rumor has it that an event has been observed. Reports caution that this could be intentionally fictitious data injected to keep scientists and journalists from over reacting. nature
This has happened before. A rather strong signal was observed on September 16, 2010, within a minute or so of its apparent arrival at the detectors. The scientists on duty at the detector sites immediately recognized the tell-tale chirp signal expected from the merger of two black holes and/or neutron stars, and sprang into action. They knew that it could be a blind injection, but they also knew to act like it was the real thing. post
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This quest to detect gravitational waves has consumed scientific lifetimes. Vern Sandberg could have also mentioned the socially innovative devices they have constructed. I feel some empathy having spent years to build a mechanism that could receive messages on another unexplored channel. See Unintended Product
See Commissioning Story for jargon filled quotes from a LIGO popular publication.