Searches for non-standard continuous gravitational waves

Spinning neutron stars are sources of long-duration continuous gravitational waves(CWs) that may be detected by modern interferometric detectors such as aLIGO. Searches for CWs are based on the match filtering data analysis, when all the
available data from an observing run is collected.
The thesis is focused on the searches for transient CWs, when the signal is not always present in the data, but instead appears at certain times for a certain duration. The practical case is that of a known neutron star with phase parameters that are not fully known. This could apply to R-mode driven gravitational radiation excited by pulsar glitches, provided that the precise timing of the glitches is not known during the observing run.
The first part of the thesis (Chapter 4) presents the first search specifically targeting R-mode emission from the fastest young pulsar PSR J0537-6910. This search is conducted during the O1 and O2 aLIGO runs, when the pulsar’s rotational arameters
and the times of the glitches are not precisely known. I find no significant signal candidate and set upper limits on the intrinsic amplitude of gravitational-wave signals. The candidates with the highest detection statistics are reported for the post-following transient searches.
In the second part of the thesis (Chapter 5) I examine the statistical properties of a multi-template search in the presence of a transient CW signal. I derive a precise form of the detection statistic (F-statistic ) which is important for characterising a
detection method.
In the third part (Chapters 6 and 7) I conduct further investigation into the performance of the multi-template search and propose a new search method that can locate a transient CW signal in time. This research allows to set up post-following searches for a transient signal using the most information that can be obtained from an initial search over all available data. This method is particularly useful when the times at which glitches disturb the pulsar’s rotation are not known from
electromagnetic searches. I demonstrate how the method can be applied to search for transient CWs from PSR J0537-6910 during the O1 Advanced LIGO observing run.