Resampling method for semi-targeted continuous gravitational wave search in the Virgo interferometer

The detection of continuous gravitational waves has to deal with the Doppler effect induced by the Earth motion with respect to the source and emission frequency slowing (spindown). The correction to be applied to the antenna output depends on the source sky direction, on the signal frequency and on the source spindown. Since these parameters are, in general, unknown a large computing effort is required to correct for any possible direction, emission frequency and spindown value. A correction technique independent of the source frequency is discussed in this thesis. The moving observer proper time is accelerated (or slowed down) by removing (or doubling) in a timely manner single samples of the detector digitized signal so to keep the synchronization to the rest clock. This technique allows to avoid the scanning of all the possible source frequency and thus allows to save a large amount of computing time in data analysis. The technique was applied to VIRGO scientific run data to search for continuous signals coming from the center of the galaxy