https://www.um.edu.mt/library/oar/handle/123456789/63158 Fri, 17 Apr 2026 13:20:11 GMT 2026-04-17T13:20:11Z https://www.um.edu.mt/library/oar/handle/123456789/141880 Title: Enhancing the northern cross radio telescope for fast radio burst searching Abstract: Fast Radio Bursts (FRBs) are short, bright radio transients whose real-time detection is critical for understanding their origins. This project evaluates and optimises the Heimdall-based detection pipeline of the Northern Cross Radio Telescope for real-time deployment. Using data generated to represent data gathered from the Northern Cross, a structured grid search was performed over key hyperparameters. Performance was quantified using detection accuracy for features including the Signal to Noise Ratio (SNR), Dispersion Measure (DM), and Time of Arrival (ToA), alongside end-to-end runtime. The optimal parameter set achieved high recovery accuracy across all metrics while maintaining processing speeds compatible with real-time operations. These results demonstrate a measurable improvement in the Northern Cross pipeline’s sensitivity–performance balance and strengthen its capability for ongoing FRB searches. Description: M.Sc.(Melit.) Wed, 01 Jan 2025 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/141880 2025-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/135557 Title: Testing new physics with precision observations Abstract: There are persisting tensions in the Hubble constant and in the σ8 parameter that have yet to be resolved. Different models have been used throughout the years in an attempt to lessen these tensions and gain more knowledge about the Universe. ΛCDM is the theoretical framework that describes the origin, structure and evolution of the Universe. However, there are several tensions between the predictions of standard cosmology and the observations of various cosmological probes, such as the Hubble constant (H0) and the σ8 parameter. By investigating a reparametrisation of the ΛCDM, more information can be obtained on these tensions and new physics can be uncovered. The main objective of this research is to examine the viability of wCDM as a solution to the observed tensions within the standard cosmological model. The Cosmic Microwave Background (CMB) radiation, a powerful probe of the early universe, plays a central role in this study by analysing CMB anisotropies and temperature fluctuations in conjunction with high-precision data from Planck data. This project also takes the opportunity to examine the new Planck likelihood (Planck 2020) with the previous one (Planck 2018) and examine the new data of Dark Energy Spectroscopic Instrument (DESI) with the previously released data set of Baryon Acoustic Oscillations (BAO). The late-time data of Pantheon + SH0ES (SN+SH0ES) and Cosmic Chronometers (CC) data will also be used to serve as a way to add tighter constraints and, therefore, more accurate values with less uncertainties. In this project, the wCDM models showed that the newer datasets of Planck and BAO contained the models better than the previously released datasets. However, the wCDM model still favoured Planck 2018 and the older BAO data. Also, the tested models all had large uncertainties and degeneracies when only early-time data was taken, but the addition of the late-time data generally decreased the degeneracies and uncertainties. These key findings are discussed in further detail in Chapter 4 Description: M.Sc.(Melit.) Wed, 01 Jan 2025 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/135557 2025-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/134917 Title: Secular evolution in the Milky Way Abstract: This work and its abstract are both under embargo until the restriction is lifted. Description: Ph.D.(Melit.) Mon, 01 Jan 2024 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/134917 2024-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/132261 Title: Cosmological predictions of scalar-tensor theories in teleparallel gravity Abstract: The cosmological tensions following observational analysis as well as the late-time cosmic accelerated expansion provide a solid motivation for the adequacy of General Relativity as the primary theory for describing gravity. Under that novel viewpoint, scalar-tensor theories are commonly utilized as the typical method for investigating potential deviations from the ΛCDM model. Scalar-tensor theories are among the most extensively examined topics of modified gravity since their dynamical analysis reveals quite interesting behaviour associated with the various eras of cosmic evolution. The capacity of scalar-tensor theories to elucidate different cosmological epochs validates the increasing interest of the scientific community in the Horndeski theory of gravity, which is considered the most general scalar-tensor theory resulting in second-order field equations. The revival of the Horndeski theory in its contemporary form has generated profound research beyond the standard model of cosmology involving the broader framework of scalartensor theories. Following the detection of the GW170817 event, the constraints imposed on the terms of the Horndeski Lagrangian served as a starting point for its incorporation into Teleparallel Gravity. This results in the Teleparallel Analogue of Horndeski theory, known as the BDLS theory, which is discussed in the current thesis, followed by the classification of its models using the Noether Symmetry Approach. The investigation of the BDLS cosmological perturbations is also included along with their potential for further research on whether the No-go argument could be circumvented in a healthy manner. Furthermore, the Einstein Gauss-Bonnet model is examined by utilizing a dynamical system approach. This scalar-tensor theory contains a highly diverse phase space due to the inclusion of the fourth-order Gauss-Bonnet invariant combined with the second-order scalar field contribution. The critical points that emerge have the potential to enhance our comprehension of cosmic evolution as they differ noticeably compared to those already present in the literature. Description: Ph.D.(Melit.) Mon, 01 Jan 2024 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/132261 2024-01-01T00:00:00Z