Dynamical models of galaxies observed in Hı line emission with MeerKAT
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Date
2025
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University of the Western Cape
Abstract
The dynamics of galaxies play a crucial role in understanding the evolution of these cosmic structures. In this work, we use neutral atomic hydrogen (Hı) emission line observations to generate 3D dynamical models of two galaxies, ESO 418- G 006 and WISEA J033235.23- 275532.8. These two galaxies form part of the Looking At the Distant Universe with the MeerKAT Array (LADUMA) survey. The first Hı interferometric observations of these extragalactic systems are constituted by this survey. Due to the exquisite nature of MeerKAT data, dynamical models of these galaxies are constructed at ˜1000 resolution, with these models used to gain insights into di↵erent evolutionary aspects of these galaxies. Using the dynamical model and resulting rotation curve of ESO 418- G 006, the first mass model of this galaxy is constructed to constrain the radial distribution properties of its dark matter content. This analysis reveals that a declining rotation curve most accurately represents the kinematics of ESO 418- G 006. Using the resulting mass model, the dark matter halo of this galaxy is parameterized using both the spherical pseudoisothermal (ISO) and NFW halo models. From this parameterization, the dark matter halo of ESO 418- G 006 is found to be best described by a halo consisting of a constantdensity inner core, with a core radius Rc = 3.79 ± 0.73 kpc and a core density ⇢0 = 0.083 ± 0.026 Mpc3. Due to the interesting morphology of the second galaxy that this work focuses on, WISEA J033235.23-275532.8, di↵erent 3D dynamical models of this galaxy are constructed, incorporating a warped Hı disk and a flat Hı disk respectively. This is undertaken to identify the model that can best describe the overall kinematics of this galaxy. Through a rigorous comparison of these models, we find that those incorporating a flat Hı disk do suciently well in resembling the data of WISEA J033235.23-275532.8. The resulting rotation curve of WISEA J033235.23-275532.8, generated from the bestfound flat Hı disk model, is found to mainly exhibit the typical shape associated with disk galaxies, but also exhibits a kinematic anomaly.
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Keywords
dynamics, galaxies, MeerKAT, models, cosmic structures