Beyond LIGO...

LIGO has detected at least two black hole mergers, illustrated here. Image credit: LIGO/A. Simonet

Topics: Astrophysics, Black Holes, Education, General Relativity, Gravitational Waves, Instrumentation, STEM

Discovery is in direct proportion to the instrumentation we currently have to detect phenomena. Thus, as our equipment gets more sophisticated, like the initial detection of Exoplanets, we'll likely encounter at least dozens more merging black holes and gravitational waves. It's why encouraging critical thinking, rationality, and science literacy - not conspiracy provocateurs, pseudo-science-word-salad-babble, Young Earth lunacy at the K-12 and secondary levels - is vital to our continued prosperity. Without it, in an increasingly technological world, we will quickly find ourselves behind...and irrelevant.

The two LIGO gravitational wave detectors in Hanford Washington and Livingston Louisiana have caught a second robust signal from two black holes in their final orbits and then their coalescence into a single black hole. This event, dubbed GW151226, was seen on December 26th at 03:38:53 (in Universal Coordinated Time, also known as Greenwich Mean Time), near the end of LIGO's first observing period ("O1"), and was immediately nicknamed "the Boxing Day event".

Like LIGO's first detection, this event was identified within minutes of the gravitational wave's passing. Subsequent careful studies of the instruments and environments around the observatories showed that the signal seen in the two detectors was truly from distant black holes – some 1.4 billion light years away, coincidentally at about the same distance as the first signal ever detected. The Boxing Day event differed from the LIGO's first gravitational wave observation in some important ways, however. [1]

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On 3 December 2015, when the European Space Agency’s (ESA’s) LISA Pathfinder spacecraft launched from French Guiana on a Vega rocket, some big questions were facing gravitational-wave astronomers. Researchers were about to find out whether getting free-falling cubes in space to stay in sync was practical. Even if the mission succeeded, no definitive proof yet existed (although the rumor mill was in full swing) that gravitational waves could be directly detected, whether in space or on the ground.

What a difference half a year makes.

Today researchers with the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced their second gravitational-wave detection, this time the result of a merger between two black holes with 14 and 8 times the mass of the Sun. These black holes are less massive but no less interesting than the already legendary black hole duo that, on 11 February, temporarily diverted the world’s attention from Donald Trump’s first presidential primary victory. [2]

1. LIGO Does It Again: A Second Robust Binary Black Hole Coalescence Observed
2. Physics Today: Looking beyond LIGO, Andrew Grant