The leading tensions to the collisionless cold dark matter (CDM) paradigm are the “small-scale controversies,” discrepancies between observations at the dwarf-galactic scale, and their simulational counterparts. In this work we consider methods to infer 3D morphological information on Local Group dwarf spheroidals and test the fitness of CDM+hydrodynamics simulations to the observed galaxy shapes. We find that the subpopulation of dwarf galaxies with mass-to-light ratio reflects an oblate morphology. This is discrepant with the dwarf galaxies with mass-to-light ratios , which reflect prolate morphologies, as well as simulations of CDM-sourced bright isolated galaxies that are explicitly prolate. Although more simulations and data are called for if evidence of oblate pressure-supported stellar distributions persists in observed galaxies while being absent from simulations, we argue that an underlying oblate non-CDM dark matter halo may be required and present this as motivation for future studies.
CITATION STYLE
Xu, W. L., & Randall, L. (2020). Testing ΛCDM with Dwarf Galaxy Morphology. The Astrophysical Journal, 900(1), 69. https://doi.org/10.3847/1538-4357/aba51f
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