Thesis
Deriving true lensing signals by minimizing shape noise using JWST multi-band observations
Master of Science (M.S.), Drexel University
Jun 2024
DOI:
https://doi.org/10.17918/00010697
Abstract
For more than two decades, gravitational lensing has become a standard tool for estimating the mass of massive objects, such as clusters of galaxies. The extent to which a background light source appears distorted depends solely on the amount of matter in the lensing object. By utilizing subtle distortions in the images of background galaxies, the weak regime of gravitational lensing provides an excellent opportunity to directly probe the baryonic and dark matter distribution of the foreground lensing objects. While shear allows mapping of large-scale structures, a higher-order lensing signal called flexion provides additional insights into the substructures. Without knowledge of the intrinsic shapes of source galaxies, the measured lensing signals, especially flexion, are significantly affected by shape noise. Utilizing JWST's multiband imaging for SMACS-J0723 and Abell 2744, it was found that shear signals are intrinsically less noisy compared to flexion signals. Shear signals measured in different bands were found to have a consistent correlation coefficient of ~ 0.95. In contrast, flexion signals, for instance aF₁, were found to have correlation coefficients of ~ 0.38 between the F115W and F356W bands, and ~ 0.51 between the F150W and F356W bands in the background galaxies of Abell 2744. By simultaneously utilizing multiband observations, the above correlations for aF₁ were found to be improved, demonstrating the derivation of approximately true lensing signals. Additionally, the optimized lensing signals were exploited to reconstruct dimensionless surface-mass densities (convergence fields) of the clusters. Finally, the convergence fields for Abell 2744, derived using shear and F-flexion, were combined to obtain high-fidelity convergence field. Consequently, the cluster's core was estimated to enclose a mass of 0.6 x 10¹⁴ [mass of Sun] within a radius of 250 kpc.
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Details
- Title
- Deriving true lensing signals by minimizing shape noise using JWST multi-band observations
- Creators
- Jeimin Amar Garibnavajwala
- Contributors
- David M. Goldberg (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- iii, 28 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- College of Arts and Sciences; Physics; Drexel University
- Other Identifier
- 991021890314004721