Weak-lensing

Weak gravitational lensing is a phenomenon in astrophysics and cosmology that occurs when the path of light from distant objects, such as galaxies, is subtly curved by the gravitational influence of intervening matter, including dark matter and galaxy clusters. This effect results in the distortion and shearing of the images of these background objects. Unlike strong lensing, where the bending of light is so significant that it creates multiple distinct images, weak lensing induces subtle, coherent distortions in the shapes of background galaxies. Weak lensing convergence maps play a crucial role in our understanding of the cosmos. These maps are generated by studying the distortion of light from distant galaxies as it passes through the gravitational influence of massive structures, such as galaxy clusters and dark matter concentrations. By measuring the apparent deformation of background galaxies, researchers construct weak lensing convergence maps that provide a unique window into the distribution of matter in the universe. Higher-order statistics, like the One-Point Probability Density Function (PDF), are essential tools in the analysis of these maps. While traditional statistics focus on averages and two-point correlations, higher-order statistics capture more complex and nuanced information. In the case of weak lensing convergence maps, they enable us to explore non-Gaussian features and rare cosmic structures that might be overlooked by simpler statistics. These higher-order measures help uncover subtle yet significant deviations from theoretical expectations, shedding light on the intricate interplay between dark matter, dark energy, and the large-scale structure of the universe. In essence, they offer a deeper and more comprehensive understanding of the intricate cosmic web and the fundamental forces shaping our universe. In my research on weak lensing convergence maps, I focus on analyzing higher-order statistics, particularly the One-Point Probability Density Function (PDF). This statistical measure allows me to study the distribution of weak lensing convergence values across the observed map. To facilitate this analysis, I employ a theoretical model that describes the expected behavior of the convergence map, helping me draw meaningful conclusions and insights about the cosmic structures and gravitational lensing effects that influence these maps. By comparing the theoretical model to observed data, I aim to uncover valuable information about the large-scale structure of the universe and the nature of dark matter and dark energy.

Topological Defects

Topological defects are fascinating cosmic phenomena that emerge during phase transitions in the early universe. They arise as a result of field configurations that cannot be continuously deformed into a trivial state, leading to the formation of topologically stable structures. One notable characteristic of topological defects is their persistence throughout cosmic history, effectively acting as active perturbation seeds that can influence the evolution of the universe. In a typical cosmological scenario, vector modes, which represent the direction of physical quantities, tend to decay rapidly and have minimal impact on the overall structure formation process. However, what sets topological defects apart is their ability to generate vector and tensor modes with magnitudes comparable to scalar modes during their formation. This unique feature has far-reaching implications for the large-scale structure of the universe. The generation of vector and tensor modes by topological defects introduces anisotropic terms into the equations governing the evolution of the universe. These anisotropic terms can manifest as distinctive signatures in the cosmic structure. To understand and study the specific impact of topological defects on structure formation, it becomes essential to employ advanced tools such as relativistic N-body simulations. These simulations provide a comprehensive framework for modeling the complex interplay between topological defects and the evolving universe, allowing scientists to explore the consequences of these defects on the cosmic web and gain valuable insights into the fundamental forces shaping our cosmos. In essence, the study of topological defects adds a unique and intriguing dimension to our understanding of the universe's large-scale structure and its origins.