Self-Interacting Dark Matter Subhalos in the Milky Way's Tides

Area of Science:

• Cosmology
• Astrophysics
• Particle Physics

Background:

• Dark matter simulations often assume cold dark matter (CDM), which predicts smooth subhalo density profiles.
• The Milky Way's tidal field can significantly alter dark matter subhalo structures.
• Observations of satellite galaxies like Draco and Fornax present challenges for standard CDM models regarding their inner dark matter content.

Purpose of the Study:

• To investigate the evolution of self-interacting dark matter (SIDM) subhalos within the Milky Way's tidal field.
• To compare the predicted dark matter distributions in SIDM subhalos with those in CDM subhalos.
• To test the viability of an SIDM model in explaining the observed properties of Milky Way satellite galaxies.

Main Methods:

• Simulating the evolution of SIDM subhalos under the influence of Milky Way tides.
• Analyzing the resulting dark matter density profiles in the inner regions of these subhalos.
• Comparing simulation results with observational data from the Draco and Fornax dwarf galaxies.

Main Results:

• SIDM subhalos exhibit more diverse dark matter distributions in their inner regions compared to CDM subhalos when subjected to tidal forces.
• The SIDM model, incorporating self-interactions, successfully accommodates the contrasting inner dark matter content observed in the Draco and Fornax satellite galaxies.
• These findings suggest SIDM can resolve discrepancies between CDM predictions and observations of galactic rotation curves.

Conclusions:

• Self-interacting dark matter provides a more flexible framework for explaining the diversity of dark matter structures in galactic environments.
• The Milky Way's tidal field plays a crucial role in shaping subhalo properties, leading to observable differences between SIDM and CDM.
• The tested SIDM model shows promise for unifying explanations for both satellite galaxy properties and the rotation curves of field spiral galaxies.