Novel Searches for Gravitational Waves from Compact Binary Coalescences

Pal, Souradeep (2025) Novel Searches for Gravitational Waves from Compact Binary Coalescences. PhD thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Accelerating charges produce electromagnetic waves, whereas accelerating masses produce gravitational waves. Terrestrial sources of gravitational waves are too weak to be detected with current technologies. Astrophysical sources can emit detectable gravitational waves as predicted by the theories of relativity. Several attempts have been made in the past to detect gravitational waves through experiments. The first definite success came in 2015 when the Advanced LIGO detectors observed transient gravitational wave signals from two colliding black holes in the distant sky. This happened soon after the twin Advanced LIGO detectors in the US began their observing runs in 2015. The Virgo detector in Italy soon joined the observations in 2017. KAGRA, an underground detector facility in Japan also started taking data in 2020. A LIGO detector in India is slated to join the global effort for detections in 2030s. Apart from these, several next-generation ground-based observatories and space-based missions are being planned and proposed. Together these detectors are poised to detect several types of astrophysical sources of gravitational waves. At the time of writing, confident detections have been made for gravitational wave signals coming from the merger of two compact objects involving black holes and/or neutron stars. Due to the effect of gravity, the compact objects inspiral around each other for several cycles before merging into a single heavier object. However, the sum of the initial masses of the individual objects is larger than the mass of the final object. An energy equivalent to the mass difference is radiated in the form of gravitational waves. Such phenomena are predicted by the theories by relativity. Signals from a few hundreds of such systems, known as compact binary coalescences, have already been identified with the current gravitational wave observatories. With detections becoming frequent and prominent, there is a need for developing computationally efficient data analysis techniques. Depending upon the nature of the sources, techniques to find their signals and to extract information about their properties are developed. This thesis explores some of the methods in detail. We discuss the development of novel techniques to search for astrophysical signals in the detector data that can be extended to the future in a sustainable way. We also explore mechanisms to probe some of the fundamental properties of the detectable sources by going beyond the existing analysis techniques. Emphasis has been on utilizing the inferred properties toward informing astronomers from the broader community about potentially interesting events. Advancements in both data analysis techniques and detector technologies would enhance the wider observational capabilities of gravitational wave observatories.

Item Type: Thesis (PhD)
Additional Information: Supervisor: Rajesh Kumble Nayak
Uncontrolled Keywords: Astrophysical Signals; Compact Binary Coalescences; Compact Binary Mergers; Gravitational Waves; Spin-Aligned Eccentric Searches; Spin-Aligned Tidal Searches
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Center of Excellence in Space Sciences, India
Depositing User: IISER Kolkata Librarian
Date Deposited: 17 Oct 2025 10:51
Last Modified: 17 Oct 2025 10:51
URI: http://eprints.iiserkol.ac.in/id/eprint/1856

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