How are Gravitational waves produced?

Effects of gravity#3 

Gravitational Waves: Ripples in space-time

Origin, facts and effects of gravitational waves 

Gravitational ripples in space-time

Gravitational waves were first predicted by Albert Einstein based on his General Theory of Relativity in 1916. Despite the skepticism over the existence of gravitational waves at that time, some physicists still believed that gravitational waves do exist and can be detected using highly sophisticated instrumentation (which was yet to be developed at that time). However, in September 2015, LIGO caught a glimpse of the first-ever direct observation of gravitational waves, that swooped across the earth by causing a wobbling effect less than the width of a proton!!   

How are gravitational waves produced?

Gravitational waves are basically disturbances in space-time, that are produced when extremely dense stars collide and merge, to form a massive black hole. It behaves in the same way as when a stone is thrown into a pond of water, disturbing the system by creating ripples in water, that emerges from the point where the stone was dropped. Gravitational waves are thought to be sent out by powerful explosions of massive stars or black holes, which act as disturbances in space-time.

1. When two black holes collide with each other

When two black holes (whether small, mediocre or supermassive) orbit each other, which is driven by their own pull of gravitation, they'll eventually collapse into each other and merge into a more massive single black hole. This merger is normally associated with a supernova, or a kilonova, in the case of two supermassive black holes. A black hole collision is considered the most energetic and powerful explosion in the universe, with jets of gases, X-rays, gamma rays, light and of course, ripples of gravitational waves that distort space-time when they pass through it.

    2.  When two neutron stars collide

Computer simulation of a neutron star collision   

This collision not only produces gravitational waves but also Gamma-Ray Bursts (GRBs), which are extremely bright and energetic. Normally, the product of this neutron star- neutron star merger possesses a very strong magnetic field, trillion times that of the earth, as neutron stars are already known for their unreal extreme magnetic fields around them. 

    3.   When two white dwarfs collide

White dwarf collisions produce gravitational waves while they're spinning and orbiting each other very closely. White dwarf mergers usually do not end up forming a black hole, rather it emerges as a dense neutron star or a new star that starts its cycle of fusion all over again. Sometimes, the collision may occur in dispersing the matter and energy of these white dwarves into space as a supernova explosion.

Effects of gravitational waves on objects

In all of the above cases, the gravitational ripples produced travel through space-time at the speed of light. Their peak frequency is during the final stage just before the merging of the two bodies.   

Gravitational waves on earth - MIT

Gravitational waves tend to wobble objects that come in their path. This is because they are distortions of space-time itself!! Since all objects are embedded in space-time, those ripples can wobble them too. Such objects (including earth) can contract or expand in their size, in an oscillatory manner, when passed by gravitational waves. This property (momentary distortion of sizes of objects) of gravitational waves is used in observatories and instruments to detect them. These ripples can affect time too, as space and time are associated with each other. Two precise synchronized clocks (showing same time) placed at different locations, can show different times after the waves have passed.