Licentiate thesis defense: Survey Astronomy with the LSST and Multimessenger Synergies

Survey astronomy has become a powerful tool for discoveries in astrophysics and cosmology. In the coming years this approach will be taken even further with the start of the ten year survey of the Large Synoptic Survey Telescope. This instrument, with its unique capabilities in temporal sampling, single-image depth, and covered sky-area, will explore wholly new parts of parameter space of known systems and the Universe. The time at which this instrument is coming online also presents a unique opportunity, given the recent discovery of multimessenger transients emitting both gravitational and electromagnetic signals, to study the population of binary neutron star mergers in the Universe. This will be scientifically beneficial, not only for studies of the astrophysics of these sources, but also for determination of fundamental cosmological parameters. Given the reach of the LSST, it is expected that this instrument will detect these binary neutron star mergers to greater distances than detectable by current and near-term gravitational wave detectors. This presents further scientific opportunity to study the selection effects for detection of these sources in gravitational waves, and also potentially to recover the undetected gravitational wave signals counterpart to the detection their associated electromagnetic emission. In this thesis I give a brief summary of survey astronomy, the LSST instrument and observing strategy, multimessenger astronomy and the use of binary neutron star mergers as cosmological standard sirens. I then outline the work I have undertaken to optimise the observing strategy of the LSST to detect binary neutron star mergers, and the determination that indeed a significant portion of these detected objects will be subthreshold to detection of their gravitational wave emission. Then I outline the current work to produce self-consistent simulations of a population of these events which will be useful for studying the combined selection function of the LSST and concurrent gravitational wave detectors. This is all preparatory work to complete the full analysis of a program to recover the gravitational waves of BNS mergers detected by the LSST but below the detection threshold of a gravitational wave detector network. I outline some of what will go into this calculation and what work we plan to do. Additionally, I discuss the importance of addressing the classification problem for
completing this scientific program.