The total mass and dark halo properties of the Small Magellanic Cloud

Abstract

We discuss the total mass and dark halo properties of the Small Magellanic Cloud (SMC) for reasonable $V$-band stellar-to-mass-to-light ratios ($M_{\mathrm{s}}/L_{\mathrm{V}}$) based on the high-resolution neutral hydrogen (HI) observations of the SMC. We adopt both the Burkert and the NFW profiles for the dark matter halo of the SMC in order to model the radial profile of the observed rotation curve. We show that the mass ($M_{\mathrm{dm}}$) and the mean density (${\rho }_{\mathrm{dm}}$) of the dark matter halo within the optical radius ($\sim 3$ kpc) of the SMC can be significantly low for $M_{\mathrm{s}}/L_{\mathrm{V}}=2-4$ reasonable for a galaxy dominated by older stellar populations. For example, the estimated $M_{\mathrm{dm}}$ and ${\rho }_{\mathrm{dm}}$ are $7.5\times 10^7{\mathrm{M}}_{\odot }$ and $6.7\times 10^{-4}{\mathrm{M}}_{\odot }$ pc${}^{-3}$, respectively, for $M_{\mathrm{s}}/L_{\mathrm{V}}=3.8$. The models with lower $M_{\mathrm{s}}/L_{\mathrm{V}}$ ($<1.0$) can show higher $M_{\mathrm{dm}}$ and ${\rho }_{\mathrm{dm}}$ yet have difficulties in reproducing the inner rotation curve profile both for the Burkert and the NFW profiles. The Burkert profile with a larger core radius ($>1$ kpc) (thus a low density) and a large mass (${\mathrm{M}}_{\mathrm{dm}}>3\times 10^9{\mathrm{M}}_{\odot }$) can be better fit to the observed slowly rising rotation curve than the NFW one for a reasonable $M_{\mathrm{s}}/L_{\mathrm{V}}\sim 2$. This means that most of the dark halo mass can be initially located outside the optical radius in the SMC and thus that the dark halo would have already lost a significant fraction of its original mass due to the strong tidal interactions with the Galaxy and possibly with the Large Magellanic Cloud (LMC).

10 pages, 9 figures, accepted by MNRAS

References in corpus (3)

• Dynamical Influences of the Last Magellanic Interaction On the Magellanic Clouds
• Formation of the Small Magellanic Cloud: ancient major merger as a solution to the kinematical differences between old stars and HI gas
• The Origin of Large-scale HI structures in the Magellanic Bridge

Cited by in corpus (20)

• Constraining mixing in massive stars in the Small Magellanic Cloud
• SatGen: a semi-analytical satellite galaxy generator -- I. The model and its application to Local-Group satellite statistics
• Search for 511 keV Emission in Satellite Galaxies of the Milky Way with INTEGRAL/SPI
• The Magellanic Inter-Cloud Project (MAGIC) III: First spectroscopic evidence of a dwarf stripping a dwarf
• STEP: The VST survey of the SMC and the Magellanic Bridge. I. Overview and first results
• The Most Metal-poor Stars in the Magellanic Clouds are $r$-process Enhanced
• The VMC survey -- XXXVIII. Proper motion of the Magellanic Bridge
• Limits on planetary-mass primordial black holes from the OGLE high-cadence survey of the Magellanic Clouds
• A Comprehensive Perturbative Formalism for Phase-Mixing in Perturbed Disks. I. Phase spirals in an Infinite, Isothermal Slab
• Re-examining the Too-Big-To-Fail Problem for Dark Matter Haloes with Central Density Cores
• Unearthing Foundations of a Cosmic Cathedral: Searching the Stars for M33's Halo
• A Comprehensive Perturbative Formalism for Phase Mixing in Perturbed Disks. II. Phase Spirals in an Inhomogeneous Disk Galaxy with a Non-responsive Dark Matter Halo
• Spatially Resolved Gas-phase Metallicity in FIRE-2 Dwarfs: Late-Time Evolution of Metallicity Relations in Simulations with Feedback and Mergers
• Microlensing optical depth, event rate, and limits on compact objects in dark matter based on 20 yr of OGLE observations of the Small Magellanic Cloud
• Modeling the Cosmic Dispersion Measure in the D < 120 Mpc Local Universe
• Star cluster formation from giant molecular clouds in the Small Magellanic Cloud about 2 Gyr ago: their origin, structures, and kinematics
• The metal-poor dwarf irregular galaxy candidate next to Mrk 1172
• A Galactic Transformation -- Understanding the SMC's Structural and Kinematic Disequilibrium
• Linearity: galaxy formation encounters an unanticipated empirical relation
• The Escape of Globular Clusters from the Satellite Dwarf Galaxies of the Milky Way