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Self-Interacting Dark Matter Can Explain Diverse Galactic Rotation Curves
Ayuki Kamada1,2, Manoj Kaplinghat3, Andrew B Pace3,4
1Department of Physics and Astronomy, University of California, Riverside, California 92521, USA.
Physical Review Letters
|September 27, 2017
Summary
The self-interacting dark matter (SIDM) model successfully explains diverse spiral galaxy rotation curves, unlike the standard cold dark matter (CDM) model. SIDM
Area of Science:
- Cosmology
- Astrophysics
- Particle Physics
Background:
- Spiral galaxy rotation curves present a challenge to the standard cold dark matter (CDM) paradigm.
- Observed diversity in rotation curves is difficult to reconcile with CDM predictions.
Purpose of the Study:
- To investigate the self-interacting dark matter (SIDM) model's ability to explain the diverse rotation curves of spiral galaxies.
- To assess SIDM's efficacy across a range of galaxy properties.
Main Methods:
- Utilized the SIDM model with a fixed self-interaction cross section.
- Assumed the halo concentration-mass relation predicted by the CDM model.
- Analyzed a sample of galaxies with asymptotic velocities from 25-300 km/s.
Main Results:
- SIDM provides excellent fits to observed galaxy rotation curves, capturing their full diversity.
- SIDM's thermalization creates large cores in dark-matter-dominated galaxies, reducing densities.
- Thermalization leads to denser, smaller cores in luminous galaxies, explaining flat rotation curves at small radii.
Conclusions:
- The SIDM model, incorporating halo concentration-mass relations and baryon effects, successfully explains diverse spiral galaxy rotation curves.
- SIDM offers a viable alternative to CDM for understanding galactic dynamics.
- The interplay between dark matter self-interactions and baryonic physics is crucial for galactic structure.
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