New Laws of Galaxy Kinematics: Challenges to the Dark Matter Paradigm
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Date
2023
Authors
Duey, Francis
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Arguably one of the most controversial topics in cosmology today is that of the “missing mass problem”. Today, there are two main competing theories that aim to address this issue: Cold Dark Matter (CDM) and Modified Newtonian Dynamics (MOND). The goal of this thesis is to directly address this issue by investigating the relationship between the visible mass of a galaxy, with its dynamical mass. A direct comparison can be made using what is referred to as the baryonic Tully-Fisher Relation (bTFR). In this thesis, we present the new WISE baryonic Tully-Fisher Relation for the Spitzer Photometry and Accurate Rotation Curves (SPARC) galaxy sample. This sample contains galaxies with improved photometry, new M/L models, and extended gas masses. An initial plot contains 62 redshift-independent galaxies whose distances were determined from either Cepheid stars, tip of the red giant branch (TRGB) stars, or supernovae. This new bTFR has a resulting slope of 4.00 ± 0.09, in agreement with predictions from MOND, and in sharp tension with values predicted by CDM models. In addition, a secondary plot containing the full 154 SPARC galaxy sample will be fit with the results from the calibration plot using distances provided by the CosmicFlows database. This new plot provides an opportunity to deduce a value of Hubble’s constant (H0) using every galaxy with an accurate rotation curve by varying the expected total baryon mass until a minimal fit is obtained. Such an experiment results in a value of H0 of 74.8 ± 1.8 (stat) ±1.5 (sys). This is especially important in context of what is known as the “Hubble tension” and leads to a statistically sound method of deducing an important constant in the MOND framework: a0. All these results and the heavy implications of such will be discussed in earnest throughout this thesis.
Description
60 pages
Keywords
dark matter, MOND, astrophysics, photometry, galaxy kinematics