Polarization states of gravitational waves detected by LIGO-Virgo antennas

TL;DR

This paper analyzes the polarization states of gravitational waves detected by LIGO-Virgo, proposing new methods for source localization and polarization recognition, to test theories of gravity and understand relativistic astrophysical processes.

Contribution

It introduces novel techniques for identifying GW polarization states using multiple detectors and applies them to LIGO events to test gravitational theories.

Findings

Opportunities to verify scalar-tensor gravity predictions

Methods successfully applied to LIGO GW events

Enhanced understanding of gravitational wave polarization

Abstract

The detection of the first gravitational wave events by the Advanced LIGO Scientific Collaboration has opened a new possibility for the study of fundamental physics of gravitational interaction. This work conducts an analysis of possible polarization states of gravitational waves (GW) radiated by the most promising types of sources to be detected by the modern interferometric antennas: coalescing compact binaries and collapsing supernovae. Several theoretical approaches to the current as well as future gravitational wave signals interpretation are discussed together with a strategy for a search for corresponding transients by means of multimessenger astronomy. One of the aims of this thesis is to develop a new method for GW source localization depending on a polarization state of an incoming GW in the case of a detection by two interferometric antennas. Additionally, there is elaborated a further method focused on a possibility to recognise different polarization states of a GW detected by means of a network with three and more antennas in operation. The both proposed methods have been applied to the LIGO events GW150914, GW151226 and LVT151012, together with the matching of the results with the currently known electromagnetic follow-ups to these GW events. The conclusion of this research is that there are opportunities for verifying different predictions of the scalar-tensor theories of gravitation by means of the analysis of the polarization states of the detected gravitational waves. All in all, this work provides a new test of the theoretical assumptions about the nature of gravity as well as about the processes in relativistic compact objects of various types.