Bachelor thesis defense by Casper Juul Lorentzen

Title: Review and Search of Continuous Gravitational Wave Radiation From Spin-down Pulsars

Abstract:
The thesis studies the theory of gravitational waves and the detection of them. This is done by deriving the linearized version of Einstein’s field equations and performing a multipole expansion thereof. This leads to the result that the leading order term responsible for gravitational wave emission is a quadrupole moment, as the time derivative of mass-energy dipoles are found to be zero in accordance with conservation laws.

In a vaccum, the waves are found to affect spacetime with two different polarizations, making it possible to detect them using two long arms perpendicular to each other. Considering the continuous gravitational wave emission of spin-down pulsars whose rotational frequencies are assumed to follow a power law with braking index n = 5, a possible search of their waves is presented, exploiting the tools of short-time Fourier analysis, stack-sliding, and differential evolution, using data from the LIGO detectors. A search run on 16 different strain amplitudes found a sensitivity of h0 = 5 × 10^−27 with a power spectral density noise of 5 × 10^−24.