The GD-1 Stellar Stream Perturber as a Core-collapsed Self-interacting Dark Matter Halo.

Area of Science:

• Astrophysics
• Cosmology
• Particle Physics

Background:

• The GD-1 stellar stream shows structures suggesting a close encounter with a dense dark matter substructure.
• This perturber's density exceeds predictions from the standard cold dark matter (CDM) model.

Purpose of the Study:

• To investigate if self-interacting dark matter (SIDM) can explain the high density of the GD-1 perturber.
• To use N-body simulations to model SIDM halo evolution and compare it with GD-1 stream observations.

Main Methods:

• High-resolution N-body simulations of a progenitor halo within the Milky Way's tidal field.
• Modeling SIDM halos with specific cross-sections (σ/m ≈ 30-100 cm²/g) undergoing gravothermal collapse.
• Comparing simulated halo properties with the inferred properties of the GD-1 perturber.

Main Results:

• A collapsed SIDM halo can achieve central densities over an order of magnitude higher than CDM counterparts within 10 pc.
• Simulated SIDM halo properties align well with the inferred characteristics of the GD-1 perturber.
• The cross-section per mass of σ/m ≈ 30-100 cm²/g is favored.

Conclusions:

• Self-interacting dark matter provides a viable explanation for the GD-1 perturber's high density.
• Stellar streams serve as a unique observational probe for studying the nature of dark matter, particularly its self-interaction properties.