In recent news, gravitational wave observatories at the Laser Interferometer Gravitational-Wave Observatory (LIGO) have made a historic detection. For the first time ever, they have identified a merger between two dissimilar mass black holes.
The GW190412 Event
This groundbreaking event, known as GW190412, took place on April 12th, 2019, nearly five years after the first-ever detection of gravitational waves by LIGO detectors on September 14th, 2015. The earlier detected signal was dubbed GW150914.
The GW190412 event entailed a merger of two black holes with markedly different masses. One weighed about 8 Solar masses and the other, approximately 30 Solar masses. These weights are measured using a solar mass unit, which is the mass equivalent to our sun or roughly 2×10³⁰ kg, a common measure in astronomy. This binary merger unfolded a staggering 2.5 billion light-years away from us.
Pioneering Findings and Implications
Significantly, this is the first instance where an unequal mass system has been found. Previous binaries observed by both LIGO and Virgo (Italy) detectors have always involved two black holes of similar masses. This discovery is poised to shed light on several new aspects, including a more accurate determination of distance from the event, a better understanding of the angular momentum or spin of the heavier black hole, and clearer perception of the event’s orientation in relation to Earth.
Differences Between Equal and Unequal Mass Binary Blackholes
One primary distinction lies in the major emission of gravitational waves. In equal mass black holes, this happens at twice the orbital frequency and is insignificant. In contrast, unequal mass black holes emit at a frequency triple that of the orbital rate. Furthermore, in the latter case, the spin of the more hefty black hole greatly influences the binary’s dynamics, becoming identifiable by extra features in the signal waveform.
The Validation of General Relativity
This observation further endorses Einstein’s theory of general relativity, published in 1915. The theory envisages the emergence of higher harmonics or gravitational waves at twice or thrice the principal frequency. It also notably anticipated the direct detection of these waves and the observation of black hole collisions and mergers.
About Black Holes and Gravitational Waves
A black hole is a region in space where gravity is so potent that it prevents anything, including light, from escaping due to matter being compressed into a minuscule space. Gravitational waves are generated when two black holes orbit each other and merge.
Laser Interferometer Gravitational Wave Observatory: LIGO
LIGO, with two widely separated interferometers stationed in Washington and Louisiana, is the world’s largest gravitational wave observatory. Its mission is to detect waves produced by some of the universe’s most turbulent and powerful processes. However, the data gathered by LIGO can influence numerous physics fields, including gravitation, relativity, astrophysics, cosmology, particle physics, and nuclear physics.
