[Paper Review] Self-Interacting Dark Matter and the Origin of NGC1052-DF2 and -DF4

Daneng Yang, Hai-Bo Yu+1 more|arXiv (Cornell University)|Feb 6, 2020

Dark Matter and Cosmic Phenomena4 citations

TL;DR

This study uses N-body simulations to test whether tidal stripping from NGC1052 can explain the low dark matter content in ultra-diffuse galaxies DF2 and DF4. It finds that self-interacting dark matter (SIDM) better reproduces the observed diffuse stellar distributions and reduced dark matter content than cold dark matter (CDM), due to enhanced tidal mass loss from core formation, making these galaxies key probes for dark matter physics.

ABSTRACT

Observations of ultra-diffuse galaxies NGC1052-DF2 and -DF4 show they contain little dark matter, challenging our understanding of galaxy formation. Using controlled N-body simulations, we explore the possibility to reproduce their properties through tidal stripping from elliptical galaxy NGC1052, in both cold dark matter (CDM) and self-interacting dark matter (SIDM) scenarios. To explain the dark matter deficiency, we find that a CDM halo must have a very low concentration so that it can lose sufficient mass in the tides. In contrast, SIDM favors a higher and more reasonable concentration as core formation enhances tidal mass loss. Stellar distributions in our SIDM benchmarks are more diffuse than CDM one, and hence the former provide a better match to the data. We further show that the presence of stellar particles is critical for preventing the halos from being totally disrupted and discuss its implications. Our results indicate that the dark matter-deficient galaxies may provide important tests for the nature of dark matter.

Motivation & Objective

• To investigate whether tidal stripping from NGC1052 can explain the low dark matter content observed in ultra-diffuse galaxies DF2 and DF4.
• To compare the viability of cold dark matter (CDM) versus self-interacting dark matter (SIDM) in reproducing the structural and dynamical properties of DF2 and DF4.
• To assess the role of stellar particles in preventing complete disruption of dark matter halos during tidal encounters.
• To determine whether the observed diffuse stellar distributions in DF2 and DF4 are better matched by SIDM or CDM halos.

Proposed method

• Conduct controlled N-body simulations of tidal encounters between NGC1052 and dwarf galaxies, modeling both CDM and SIDM halos.
• Use a range of halo concentrations and initial orbital parameters to explore parameter space for matching observed properties.
• Implement self-interactions in dark matter via a cross-section of σ/m ≈ 1 cm²/g to simulate core formation in SIDM.
• Include stellar particles in the simulations to assess their role in stabilizing halos against complete disruption.
• Compare simulated structural and kinematic properties (e.g., stellar distribution, mass loss) with observational data on DF2 and DF4.
• Evaluate the consistency of simulated outcomes with observed low dark matter fractions and diffuse stellar profiles.

Experimental results

Research questions

• RQ1 Can tidal stripping from NGC1052 reproduce the low dark matter content observed in DF2 and DF4 within the CDM framework?
• RQ2 Does self-interacting dark matter (SIDM) provide a better match to the observed diffuse stellar distributions in DF2 and DF4 than CDM?
• RQ3 How does the presence of stellar particles affect the survival and structural evolution of dark matter halos during tidal encounters?
• RQ4 What halo concentration is required in CDM and SIDM to achieve sufficient mass loss and match observations?
• RQ5 Can the observed properties of DF2 and DF4 serve as a discriminant between CDM and SIDM models?

Key findings

• In the CDM scenario, a very low halo concentration is required to achieve sufficient tidal mass loss, which is physically implausible.
• In the SIDM scenario, core formation enhances tidal mass loss, allowing a higher and more realistic halo concentration to reproduce the observations.
• Stellar distributions in SIDM simulations are more diffuse than in CDM, providing a better match to the observed diffuse morphology of DF2 and DF4.
• The presence of stellar particles is critical for preventing complete disruption of dark matter halos during tidal encounters.
• SIDM halos exhibit enhanced tidal stripping efficiency due to core formation, making them more consistent with the observed low dark matter content.
• The results suggest that dark matter-deficient galaxies like DF2 and DF4 may serve as key tests for the nature of dark matter, particularly distinguishing between CDM and SIDM.