First merger of two black holes with unequal masses detected

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. 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.

Highlights

• On April 12, 2020, the LIGO-Virgo collaboration detected collision between two black holes that were 2.4 billion light years away.
• This is the first such discovery involving two black holes of unequal mass.
• The incident is named GW190412.
• This incident was detected in the year 2019.
• About 5 years ago the Gravitational Observatory at LIGO first detected gravitational waves.
• The mass of both these black holes was 8 solar masses and 30 solar masses respectively.
• Solar mass refers to the mass of the Sun, which is 2 × 108 kilograms.
• It is a standard unit of mass in astronomy.
• The scientists have now concluded from their researches and analysis that these black holes were of unequal masses.
• The black holes were 20 and 40 times the mass of the sun.
• One of the black holes was 29.7 solar masses and the other was 8.4 solar masses.
• Though they are heavier and uneven, they are the lowest-mass black holes recorded so far.
• Solar Mass is the standard of mass in astronomy that is used to indicate masses of other masses. One solar mass is equal to 2×1030 Kg.

Laser Interferometer Gravitational Wave Observatory:

• LIGO is the world’s largest gravitational wave observatory.
• LIGO consists of two widely separated interferometers within the United States – one in Hanford, Washington and the other in Livingston, Louisiana – operated in unison to detect gravitational waves.
• Though its mission is to detect gravitational waves from some of the most violent and energetic processes in the Universe, the data LIGO collects may have effects on many areas of physics including gravitation, relativity, astrophysics, cosmology, particle physics, and nuclear physics.

Black hole

• A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space.
• Gravitational waves are created when two black holes orbit each other and merge.

Difference between binary blckholes of equal masses and unequal masses:

• Dominant emission of gravitational waves happens at twice the orbital frequency of the binary blackholes of equal masses and is negligible.
• In binary blackholes with unequal masses, the emission happens at a frequency that is three times the orbital frequency.
• Orbital frequency is a scalar measure of rotation rate.
• Also, in the merger of unequal black holes, the spin of the more massive black hole can be determined from the extra features in the signal waveform.
• The spin of the heavier black hole plays a more prominent role in the dynamics of the binary.

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