December 18, 2017

16.03.11: The LIGO/Virgo Collaboration Passes “The Envelope.”

On the hunt for Gravitational Waves in the heart of Louisiana… (Photo by Author).

Amidst a week of killer-moons and earthquake paranoia, a real science story with potentially big implications was shaping up in Arcadia, California.  On March 14th, the LIGO (Laser Interferometer Gravitational Wave Observatory) and European-based Virgo scientists gathered to “pass the envelop” (their spelling!) On a hoped-for first detection of a gravitational wave. Amber Stuver, aka @livingligo on Twitter and a researcher at LIGO Livingston, recounts on her blog how she received a 1 AM text message concerning the potential detection as one of 25 select researchers notified and kept it mum for 6 months. The bogie was a potential source in the constellation Canis Major and the pulse looked like just what one would suspect from a binary pulsar merger.

Like the proverbial Schrödinger’s’ Cat hypothesis, the envelope would be potentially empty (no detection) or full (detection or injection) until the event, in this case with a thumb drive plus PowerPoint analysis. In the case of the September 16th, 2010 event, the verdict was… an injection, placed by the LIGO inner sanctum to verify the sensitivity of the detectors.

Why is a this a big deal? This demonstrates that the teams at the Italy-based Virgo detector and the twin LIGO detectors in the United States would have nabbed a real event if it had come to pass. Gravity waves pass through our planet at the speed of light, and a signature signal would have a spatial directionality as seen from the three detectors that would rule out a local source. When online and steady, the detectors have an effective range to detect an inspiral event out to 15 mega-parsecs, and have already placed constraint limits on pulsar-black hole mergers as well as gravity waves that could have been generated by the Big Bang itself. Curiously, the last generated injection was the infamous Equinox Event in 2007, also a September injection. LIGO is a proof of concept, and as future systems such as Advanced LIGO are scheduled to go online in 2014 with 10 times the sensitivity, the Vegas odds of a positive first detection of gravity waves may reach 1:1 very soon!          

 

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