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• Gravitational Waves
• Pulsars

We are at an interesting point in the development of the human race. This is the first time in our history that we are sufficiently advanced enough to measure subtle fluctuations in the fabric of space and time. Of course, we are not quite there yet. Many nations are building dedicated ground based instruments capable of measuring distances to an accuracy of one part in ten thousand billion billion, the precision required to measure these space-time fluctuations which are commonly referred to as gravitational waves. These ground based gravitational wave observatories have been in operation for almost ten years now. Through hard work and dedication, these machines are steadily approaching a sensitivity level that will make it possible to detect gravitational waves for the first time. After this event, our understanding of the universe will be forever changed.....

What if we were not confined to stay on this world? When it comes to detecting gravitational waves, bigger is better, to a point. Detecting gravitational waves requires us to measure changes in distance between two locations. The greater the initial separation, the larger the change generated by the gravitational wave. Ground based observatories are limited to a few kilometers. Imagine if we had the entire Galaxy to play with!

This is exactly what an international group of scientist are currently developing with Arecibo as the lead instrument. The North American Nano Hertz Gravitational Wave Observatory, known as NANOGrav, is a collaboration of researchers from the US and Canada. There primary goal is to detect gravitational waves by observing an exotic class of star known as a radio pulsar.

Discovered over 40 years ago, pulsars are the remains of a dying star. They are more massive then the Sun but only twenty kilometers across. These stars are observed to emit regular bursts of radio radiation. The observed regularity can be used to determine local environment of the star. As the star moves towards or away from us, our telescope will observe the emitted pulses to arrive a little earlier or later. Hence, pulsars can be used to detected the presence of gravitational waves.

The members of NANOGrav have a challenging task ahead of them. Like the ground based observatories, the pulsar based technique needs to be further developed in order to make it a viable method of gravitational wave detection. Currently, NANOGrav scientists are working on many aspects of the problem which include searching the galaxy for more radio pulsars that are suitable for gravitational wave detection, developing techniques to better measure the arrival time of radio pulses, and performing long term observations of currently know pulsars. NANOGrav is also forging relationships with other international teams with similar goals like the Parkes Pulsar Timing Array (PPTA) and the European Pulsar Timing Array (EPTA). Working together, these groups will make enormous progress in our ability to detect gravitational waves using pulsar observations. It is possible that the NANOGrav scientists and there collaborators may even be the first to find direct evidence of gravitational waves.