Gravitational Wave Observations

GW190412: The first merger of two black holes with unequal masses


From UPSC perspective, the following things are important :

Prelims level: General Relativity, Black Holes, Black Holes merger

For the first time since it started functioning, the gravitational wave observatories at LIGO scientific collaboration have detected a merger of two unequal-mass black holes.

This newscard contains few basic terms that one must know-

Gravitational waves

General Relativity

Black Holes


  • The event, dubbed GW190412, was detected nearly a year ago, and this is almost five years after the first-ever detection of gravitational-wave signals by these powerful detectors.
  • Subsequent analysis of the signal coming from the violent merger showed that it involved two black holes of unequal masses coalescing.
  • One of them was some 30 times the mass of the Sun and the other which had a mass nearly 8 times the solar mass.
  • The actual merger took place at a distance of 2.5 billion light-years away.

Significant feature observed

  • The detected signal’s waveform has special extra features in it when it corresponds to the merger of two unequal-sized black holes as compared with a merger of equal-sized black holes.
  • These features make it possible to infer many more things about the characters such as- a more accurate determination of the distance from the event, the spin or angular momentum of the more massive black hole and the orientation of the whole event with respect to viewers on Earth.
  • While the mass of the black hole bends the space-time close to it, the spin or angular momentum of this inscrutable object drags the nearby space-time, causing it to swirl around, along with it.
  • Hence both these properties are important to estimate.

Confirmed General Relativity

  • An Indian team consisting of researchers verified the consistency of the signal with the prediction of General Relativity.
  • The existence of higher harmonics was itself a prediction of General Relativity.

Must refer for an easy and illustrated understanding of General Relativity-


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