A study of supersymmetric decaying dark matter models
Date
2023
Authors
Deshpande, Meera
Editors
Advisors
Williams, White, Martin J. Anthony G.
Journal Title
Journal ISSN
Volume Title
Type:
Thesis
Citation
Statement of Responsibility
Conference Name
Abstract
The current cosmological model, CDM, has made many successful predictions about the Universe including the statistics of weak gravitational lensing, the existence of the baryon acoustic oscillations, and the cosmic microwave background and its angular power spectrum. However, recent observations of the Universe have challenged the model’s validity and revealed many discrepancies in its parameters. Two such widely researched cosmological tensions are the Hubble and Sigma-8 (S8) tension. While the Hubble tension is associated with the expansion rate of the Universe, the S8 parameter quantifies the amplitude of its matter fluctuations. Measurements of weak gravitational lensing at low redshifts (late Universe) prefer weaker matter clustering amplitude than the measurements derived from the cosmic microwave background, leading to cosmological tension. Such cosmological anomalies have motivated studies into decaying dark matter and the role of new particles called SuperWIMPs (SWIMPs) for tension resolutions. The decay of a cold dark matter particle into a massive warm dark matter and a massless dark radiation decay product has been shown to resolve the S8 tension. In this work, we build on this dark matter model by proposing a two-step decaying dark matter scenario resulting from the interplay between the Standard Model particles and supersymmetric dark matter candidates to resolve the S8 and H0 tension. For the first decay, we consider a parent cold dark matter particle (SWIMP) and radiation, with significant energy injected into the Universe. Later, as the second decay, the SWIMP further decays into massive warm dark matter and massless dark radiation daughter particles. This decay causes a suppression of the power spectrum and decreases S8 at lower redshifts. As a result, this decay model can provide a mechanism for resolving the S8 tension. Accompanying this framework, we modified a publicly available Boltzmann code, CLASS, to handle the complex decays primarily parametrized by decay parameters such as the decay width, the fraction of parent dark matter decay, and energy released into the plasma. As SWIMPs are super-weakly interacting in nature, they may be impossible to detect in the current SUSY dark matter searches in colliders and indirect/direct dark matter detection experiments. However, we successfully show that cosmological observations such as the CMB power spectrum and anisotropies can extensively probe and constrain SWIMP parameter spaces currently beyond the reach of other experiments. This work is based on the following, • A paper, ‘Cosmological constraints on supersymmetric SWIMPs,’ soon to be submitted to arxiv. • Modified version of CLASS to handle our two-step dark matter decay model, which can be found at GitHub: git@github.com:astrogirl1/ddmpy.git.
School/Discipline
School of Physics, Chemistry and Earth Sciences
Dissertation Note
Thesis (MPhil) -- University of Adelaide, School of Physics, Chemistry and Earth Sciences, 2023
Provenance
This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals