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Bulgeless dwarf galaxies and dark matter cores from supernova-driven outflows
F Governato1, C Brook, L Mayer
1Astronomy Department, University of Washington, Seattle, Washington 98195, USA.
Nature
|January 16, 2010
Summary
New simulations show that supernova-driven outflows can resolve the cold dark matter (CDM) problem in dwarf galaxy formation. This resolves the discrepancy between CDM theory and observed dwarf galaxy properties.
Area of Science:
- Astrophysics
- Cosmology
- Galaxy Formation
Background:
- The standard cold dark matter (CDM) model struggles to explain the observed properties of dwarf galaxies.
- Dwarf galaxies typically exhibit rotating stellar disks, massive dark matter halos, and constant-density cores, contrasting with CDM predictions of dense bulges and steep central dark matter profiles.
- Existing models have failed to reconcile theoretical predictions with observational data for present-day dwarf galaxies, posing a significant challenge to the CDM model.
Purpose of the Study:
- To investigate whether resolving the inhomogeneous interstellar medium in hydrodynamical simulations can reconcile dwarf galaxy properties with the CDM model.
- To determine if specific physical processes within simulations can naturally produce the observed characteristics of dwarf galaxies.
Main Methods:
- Conducted hydrodynamical simulations within a framework that includes CDM and a cosmological constant.
- Focused on resolving the inhomogeneous interstellar medium to accurately model gas dynamics.
- Analyzed the impact of supernova-driven outflows on gas and dark matter distribution in simulated galaxies.
Main Results:
- Simulations demonstrate that strong outflows from supernovae effectively remove low-angular-momentum gas.
- This process inhibits the formation of dense stellar bulges.
- Crucially, these outflows reduce the central dark matter density by more than half within the central kiloparsec.
Conclusions:
- The simulations naturally produce dwarf galaxy analogues that are bulgeless and possess shallow central dark matter profiles.
- This resolves the long-standing challenge dwarf galaxies pose to the CDM model.
- The findings suggest that the CDM model remains viable for explaining galaxy formation, including dwarf galaxies, when complex baryonic physics are accurately incorporated.
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