© 2018 by Janelle E. Letzen, PhD

 
Gravitational Waves
Meet the Scientist
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My name is Emma (@emmanigma_ on Instagram; emmalouiseosborne.com), I'm a theoretical astrophysicist studying for my PhD in Southampton, UK and a member of the LIGO Scientific Collaboration. 

Science Snack

I'm researching how neutron stars make gravitational waves by growing mountains. Neutron stars are the size of a small city and 1.4 times heavier than the sun, making them one of the most compact known objects in the universe. Neutron stars have incredibly strong gravitational and magnetic fields. These extreme environments make neutron stars excellent laboratories for testing the laws of physics to their limits!

To make gravitational waves all you need to do is wiggle some mass. This means we make gravitational waves everytime we move. The problem is gravity is weak, making it impossible to detect the gravitational waves that we produce.

 

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Neutron stars are the roundest known objects in the universe. To make gravitational waves they need to change shape and they do this by a process called accretion. Accretion occurs when a neutron star has a companion star like our sun. The neutron star's gravitational field draws matter from the companion star on to its surface causing mountains to grow. As the neutron star spins, the mountain 'hooks' onto spacetime, stirring it up, producing gravitational waves. A mountain just a couple of millimetres tall is all that is needed to produce a gravitational wave signal that's detectable on earth.

References

[1] Piro, A. L., & Thrane, E. (2012). Gravitational waves from fallback accretion onto neutron stars. The Astrophysical Journal, 761(1), 63.