Third time's a charm: LIGO detects gravitational waves for a third time

LIGO Scientists Detect Gravitational Waves For A Third Time

LIGO Detects Gravitational Waves From Merging Black Holes For Third Time

This fills in a gap between the masses of the two merged black holes detected previously by LIGO, which had solar masses of 62 (first detection) and 21 (second detection).

The black holes in the first and second detections are located 1.3 and 1.4 billion light-years away, respectively.

Albert Einstein predicted gravitational waves as part of his theory of general relativity more than 100 years ago, but it has taken astrophysicists more than 50 years of trial and error to find the direct evidence to support his theory.

"Once is chance, twice is coincidence, thrice is a pattern", wrote Michael Schirber, corresponding editor for the journal Physics, in a synopsis published with the observation of the event catalogued as GW170104, appearing June 2 in Physical Review Letters.

Like both of its predecessors, the latest gravitational wave is believed to have been created after the merger of two black holes - in this instance, black holes that were 31 times and 19 times the mass of our Sun merged to produce a single object of almost 49 solar masses, according to BBC News.

"It looks like Einstein was right - even for this new event, which is about two times farther away than our first detection", said Georgia Tech researcher Dr. Laura Cadonati, Deputy Spokesperson of the LIGO Scientific Collaboration.

"Now we have three pairs of black holes, each pair ending their death spiral dance over millions or billions of years in some of the most powerful explosions in the universe".

The new detection occurred during LIGO's current observing run, which began November 30 past year.

Among the advances achieved in the upgraded version called Advanced LIGO is the addition of a more stable laser which will become the basis for third generation gravitational wave detectors that will make gravitational wave detection a routine occurrence.

"We are moving in a substantial way away from novelty towards where we can seriously say we are developing black-hole astronomy", said David Shoemaker, a physicist at MIT and spokesman for the LIGO Scientific Collaboration, reported the New York Times.

LIGO scientists, including those from India, have for the third time successfully detected gravitational waves - ripples in space and time - generated by a merger of two massive black holes three billion light years away from Earth. Twin detectors, one in Hanford, Washington, and the other in Livingston, Louisiana, carry out LIGO's observations.

These are collisions that produce more power than is radiated as light by all the stars and galaxies in the universe at any given time. The black holes are spinning in a non-aligned fashion, which means they have different orientations relative to the overall orbital motion of the pair.

"The discovery provided the first evidence that black holes in binary systems may not be aligned", said Professor Susan Scott, from the Australian National University.

There are two primary models to explain how binary pairs of black holes can be formed. "And if that's the case, then globular clusters could be where black holes often collide and create gravitational waves". Image credit: LIGO / Caltech / MIT / Sonoma State / Aurore Simonnet.

GW170104 hints that at least one of the two black-hole spins might be misaligned with the binary orbit, mildly favoring the formation theory of dense stellar clusters. A list of additional partners is available here.

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