The degeneracy of M33 mass modelling and its physical implications

Abstract

The Local Group galaxy M33 exhibits a regular spiral structure and is close enough to permit high resolution analysis of its kinematics, making it an ideal candidate for rotation curve studies of its inner regions. Previous studies have claimed the galaxy has a dark matter halo with an NFW profile, based on statistical comparisons with a small number of other profiles. We apply a Bayesian method from our previous paper to place the dark matter density profile in the context of a continuous, and more general, parameter space. For a wide range of initial assumptions we find that models with inner log slope ${\gamma }_{\mathrm{in}}<0.9$ are strongly excluded by the kinematics of the galaxy unless the mass-to-light ratio of the stellar components in the $3.6\mu$m band satisfies ${{\rm Y}}_{3.6}\ge 2$. Such a high ${{\rm Y}}_{3.6}$ is inconsistent with current modelling of the stellar population of M33. This suggests that M33 is a galaxy whose dark matter halo has not been significantly modified by feedback. We discuss possible explanations of this result, including ram pressure stripping during earlier interactions with M31.

arXiv comment10 pages, 10 figures. Accepted by ApJ

References in corpus (29)

• The Structure of Cold Dark Matter Halos
• The Milky Way in Molecular Clouds: A New Complete CO Survey
• The Structure of Dark Matter Haloes in Dwarf Galaxies
• THINGS: The HI Nearby Galaxy Survey
• At the heart of the matter: the origin of bulgeless dwarf galaxies and Dark Matter cores
• High-Resolution Rotation Curves and Galaxy Mass Models from THINGS
• Observational and Theoretical Constraints on Singular Dark Matter Halos
• The cored distribution of dark matter in spiral galaxies
• The dependence of dark matter profiles on the stellar to halo mass ratio: a prediction for cusps vs cores
• Mass loss from dwarf spheroidal galaxies: the origins of shallow dark matter cores and exponential surface brightness profiles
• The Extended Rotation Curve and the Dark Matter Halo of M33
• Mass Models for Low Surface Brightness Galaxies with High Resolution Optical Velocity Fields
• The Metallicity Dependence of the CO-to-H${}_2$ Conversion Factor from Observations of Local Group Galaxies
• High-resolution dark matter density profiles of THINGS dwarf galaxies: Correcting for non-circular motions
• Reconstructing the stellar mass distributions of galaxies using S4G IRAC 3.6 and 4.5 micron images: II. The conversion from light to mass
• Dark matter and visible baryons in M33
• Halo expansion in cosmological hydro simulations: towards a baryonic solution of the cusp/core problem in massive spirals
• Maximum Feedback and Dark Matter Profiles of Dwarf Galaxies
• High Resolution Optical Velocity Fields of 11 Low Surface Brightness Galaxies
• Dwarf Galaxy Dark Matter Density Profiles Inferred from Stellar and Gas Kinematics
• Improved Modeling of the Mass Distribution of Disk Galaxies by the Einasto Halo Model
• Dynamical signatures of a LCDM-halo and the distribution of the baryons in M33
• A Revised LCDM Mass Model For The Andromeda Galaxy
• The Core-Cusp Problem in Cold Dark Matter Halos and Supernova Feedback: Effects of Oscillation
• The Baryons in the Milky Way Satellites
• Formation of a giant HI bridge between M31 and M33 from their tidal interaction
• Dark matter in disk galaxies I: a Markov Chain Monte Carlo method and application to DDO 154
• Dark Matter In Disk Galaxies II: Density Profiles as Constraints on Feedback Scenarios
• A link between feedback outflows and satellite galaxy suppression

Cited by in corpus (8)

• The global stability of M33: still a puzzle
• The Einasto model for dark matter haloes
• Attack of the Flying Snakes : Formation of Isolated HI Clouds By Fragmentation of Long Streams
• Classifying and modelling spiral structures in hydrodynamic simulations of astrophysical discs
• The dynamical structure of broken power-law and double power-law models for dark matter haloes
• Testing baryon-induced core formation in $\Lambda$CDM: A comparison of the DC14 and coreNFW dark matter halo models on galaxy rotation curves
• SpheCow: flexible dynamical models for galaxies and dark matter haloes
• Non-Parametric Attenuation Curves in Local Star-Forming Galaxies: Geometry Effect, Dust Evolution, and ISS