Topics Covered: Awareness in space.
First merger of two black holes with unequal masses detected
What to study?
For Prelims and Mains: About blackholes, LIGO and theory of general relativity, and gravitational waves.
Context: The gravitational wave observatories at LIGO scientific collaboration have detected a merger of two unequal-mass black holes. The event has been named as GW190412.
This is the first such observation involving two black holes of unequal masses coalescing.
Significance of the discovery:
This observation once again confirms Einstein’s theory of general relativity, which predicts the existence of higher harmonics, i.e. gravitational waves at two or three times the fundamental frequency.
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.
Also, in the case of 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. Hence, it leaves a stronger imprint on the waveform, making it easy to measure
What is a black hole?
A black hole is an object in space that is so dense and has such strong gravity that no matter or light can escape its pull. Because no light can escape, it is black and invisible.
- There’s a boundary at the edge of a black hole called the event horizon, which is the point of no return — any light or matter that crosses that boundary is sucked into the black hole. It would need to travel faster than the speed of light to escape, which is impossible.
- Anything that crosses the event horizon is destined to fall to the very centre of the black hole and be squished into a single point with infinite density, called the singularity.
Sources: the Hindu.
