Humming Sound in Universe

Recently, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) have heard the gravitational wave background which is also called as the resonant 'hum'. The findings from the observation have been published in the Astrophysical Journal Letters.


  • The NANOGrav has been deployed to study the signals from distant pulsars.
  • These distant pulsars are usually referred as the timekeepers of the Universe.
  • These pulsars emit the radio waves in order to collect the data that indicate the effects of gravitational waves.
  • However, it is still unclear whether these strong signals are coming from the Gravitational force or not.


NANOGrav is an Observatory to study and detect the Gravitational Waves. The observatory also detects the any change in the Earth’s position as a result of the stretching and shrinking of the gravitational wave. The change is detected by studying the timing of the regular signals coming from different pulsars which are scattered over the sky at the same time. It is known as a “pulsar timing array,”.  The NANOGrav mission has been implemented by the Parkes Pulsar Timing Array, European Pulsar Timing Array and International Pulsar Timing Array.

Pulsar Timing Array

It is a set of pulsars that is analyzed to search for correlated signatures. These correlated signatures are searched in the pulse arrival times. The pulsar timing arrays are done with the help of applications. One such application is using an array of millisecond pulsars so as to detect and analyse the gravitational waves.

Gravitational Waves

These are the disturbances in the curvature of spacetime. The gravitational waves are generated by accelerated masses propagating as waves at the speed of light. Henri Poincare had proposed the gravitational waves in the year 1905 and predicted by Albert Einstein 1916 after his general theory of relativity. These waves transport the energy as gravitational radiation.

Written by IAS POINT

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