Thesis
Mass reconstruction using flexion: incorporating flexion analysis into LensTools
Bachelor of Science (B.S.), Drexel University
21 May 2021
DOI:
https://doi.org/10.17918/00001984
Abstract
Gravitational lensing is amongst the most powerful tools for measuring dark and luminous matter distributions in galaxies and galaxy clusters. Lensing manifests itself as distortions in images of lightemitting galaxies; such distortions are widely measured as a statistical quantity named shear, which is defined as the induced ellipticity of galaxies. However, extending this measurement to higher order distortions gives rise to a quantity named flexion, which has proven to contain significant further information on substructures within galaxy clusters. Both shear and flexion fields can be used to reconstruct the density field, also known as the convergence. These three lensing fields manifests as distinct distortions in images of galaxies: shear is responsible for elongation, flexion for skeweness and arciness, and convergence for magnification. LensTools is a Python package capable of performing shear-convergence reconstruction, along with many other useful routines used in weak gravitational lensing. This thesis outlines the methods of implementing into the LensTools pipeline a flexion convergence reconstruction routine, which was tested/verified using simulated lensing fields from a Singular Isothermal Sphere (SIS) model. Once implemented, we reconstructed the matter distribution in the galaxy cluster Abell 2744 (A2744) using only flexion-convergence reconstruction. Using Gaussian Mixture Models (GMM) at various peaks in the density field, we identified the substructure within A2744 and using Monte Carlo integration we found the corresponding masses. The total mass of the mapped cluster was found to be (4.00 ± .038) x 10⁴⁴ h⁻¹ kg or (2.00 ± .019) x 10¹⁴ h⁻¹ solar masses.
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Details
- Title
- Mass reconstruction using flexion
- Creators
- Brij R. Patel - Drexel University, Drexel University (1970-)
- Contributors
- David M. Goldberg (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Bachelor of Science (B.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- 24 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- College of Arts and Sciences; Physics; Drexel University
- Other Identifier
- 991021872713204721