Journal
ASTROPHYSICAL JOURNAL
Volume 905, Issue 2, Pages -Publisher
IOP Publishing Ltd
DOI: 10.3847/1538-4357/abc623
Keywords
Modified Newtonian dynamics; Triangulum Galaxy; Barred spiral galaxies; Hydrodynamical simulations; Stellar dynamics; Galaxy evolution
Categories
Funding
- Alexander von Humboldt Foundation
- Agence Nationale de la Recherche (ANR) [ANR-18-CE31-0006, ANR-19-CE31-0017]
- European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program [834148]
- FONDECYT Regular [1181708]
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The dynamical stability of disk galaxies is sensitive to whether their anomalous rotation curves are caused by dark matter halos or Milgromian dynamics (MOND). We investigate this by setting up a MOND model of M33. We first simulate it in isolation for 6 Gyr, starting from an initial good match to the rotation curve (RC). Too large a bar and bulge form when the gas is too hot, but this is avoided by reducing the gas temperature. A strong bar still forms in 1 Gyr, but rapidly weakens and becomes consistent with the observed weak bar. Previous work showed this to be challenging in Newtonian models with a live dark matter halo, which developed strong bars. The bar pattern speed implies a realistic corotation radius of 3 kpc. However, the RC still rises too steeply, and the central line-of-sight velocity dispersion (LOSVD) is too high. We then add a constant external acceleration field of 8.4 x 10(-12) m s(-2) at 30 degrees to the disk as a first-order estimate for the gravity exerted by M31. This suppresses buildup of material at the center, causing the RC to rise more slowly and reducing the central LOSVD. Overall, this simulation bears good resemblance to several global properties of M33, and highlights the importance of including even a weak external field on the stability and evolution of disk galaxies. Further simulations with a time-varying external field, modeling the full orbit of M33, will be needed to confirm its resemblance to observations.
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